Health Education Research, Vol. 17, No. 1, 99-116,
February 2002
© 2002 Oxford University Press
Evaluation of a nurse-managed minimal-contact smoking cessation intervention for cardiac inpatients
Department of Social Sciences, Netherlands Open University, PB 2960, 6401 DL Heerlen and
1 Departments of Health Education, and
2 Methodology and Statistics, Maastricht University, PB 616, 6200 MD Maastricht, The Netherlands
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Abstract |
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This study examined the effectiveness of a nurse-managed minimal-contact smoking cessation intervention for patients hospitalized for cardiac disease. A pre-test–post-test quasi-experimental design was used. Patients who smoked prior to admission to cardiac wards of five hospitals (n = 388) received the intervention, whereas smoking patients in six other hospitals were given usual care (n = 401). The intervention was initiated at the hospital and continued after discharge. The core elements were stop-smoking advice from the cardiologist, a short bedside consultation with a nurse, administration of self-help materials and aftercare by the cardiologist. Smoking cessation was assessed after 3 months by self-report. Logistic regression analysis excluding dropouts, controlling for covariates including baseline differences showed significant intervention effects (one-tailed significance test) on point prevalence abstinence (OR = 2.11) and continuous abstinence (OR = 1.41). Intention-to-treat analysis including dropouts as smokers showed a significant effect on point prevalence abstinence (OR = 1.35). We conclude that, compared to usual care, the low-intensity smoking cessation intervention for cardiac inpatients was more effective in achieving smoking cessation. However, the small effects and the process evaluation suggest that improvements are needed.
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Introduction |
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Smoking cessation is known to improve the prognosis of patients with coronary heart disease (CHD) more than any other treatment (US Department of Health and Human Services, 1990
; Deckers et al., 1994; Smith, 1997; Mehta and Eagle, 1998). A meta-analysis has shown that smoking cessation among patients with newly established CHD reduces the risk of mortality after 1 year by almost 50% (Deckers et al., 1994), while smoking cessation after a first myocardial infarction reduces the risk of recurrence by half (Mulcahy, 1983; Voors et al., 1996).
Despite these promising effects, 20–60% of cardiac patients who smoked prior to their hospital admission persist in their smoking behavior or relapse after hospital discharge (Perkins, 1988; Orleans et al., 1990; Taylor et al., 1990; Rigotti et al., 1991, 1994; Ockene et al., 1992; Rose and Colwell, 1992; Deckers et al., 1994; Huijbrechts et al., 1996).
Admission to a cardiology ward is often referred to as an excellent opportunity for a smoking cessation intervention, because at that time patients are more aware of their personal vulnerability to the dangers of smoking, are highly motivated to quit and are more receptive to a smoking cessation intervention than in other circumstances (Emmons and Goldstein, 1992; Orleans and Ockene, 1993; Orleans et al., 1993b; US Department for Health and Human Services, 1996; Miller et al., 1997). In addition, patients often have been smoke-free for a period of days and may therefore be more willing to continue non-smoking.
Unfortunately, coronary care nurses and cardiologists show little effort in supporting patients to quit smoking. Although cardiologists usually advise patients to stop smoking (Van Berkel et al., 1999), only a few actually support patients in the cessation process (Sanders et al., 1986; Goldstein et al., 1987; Duncan et al., 1991; Frank et al., 1991; Emmons and Goldstein, 1992; Tessier et al., 1995). Dutch research has revealed that only one-third of all coronary care nurses addressed the smoking behavior of their patients, while only 10% of the nurses and specialists assisted patients in their attempts to quit (NIPO, 1995; Wiebing and Baan, 1997).
The objective of the present study was to assess the effectiveness of a nurse-managed minimal-contact smoking cessation intervention for patients hospitalized for CHD. A minimal-contact approach was chosen for three reasons. First, a needs assessment among Dutch coronary care nurses has revealed that nurses were only willing to spend 15–30 min on smoking cessation assistance (Working Group-West of the Netherlands Foundation on Cardiovascular Nursing, pers. commun.). Second, cardiac inpatients have expressed minimal interest in formal treatment (Fiore et al., 1990; Glynn et al., 1990; Emmons and Goldstein, 1992), while showing considerable interest in self-help guidance and brief counseling (Emmons and Goldstein, 1992). Third, several reviews have suggested that brief treatments including stop-smoking advice and brief counseling, combined with self-help and brief follow-up care are acceptable to patients, cost-effective and feasible within existing hospital practices (Miller, 1993; Orleans et al., 1993a,b). Meta-analyses constituting the basis for the development of the Clinical Practice Smoking Cessation Guidelines, released in the US in 1996 (US Department for Health and Human Services, 1996) and in the UK in 1998 (Raw et al., 1998), confirmed that these steps were essential and effective.
The Minimal Intervention Strategy for cardiac inpatients (C-MIS), which is the topic of the present paper, is based on the Minimal Intervention Strategy for smoking cessation in general practice (MIS). MIS has proved its efficacy and feasibility in general practice in a large randomized controlled trail, where it resulted in 12-month cessation rates of 17.5%, compared to 9% in the usual care group (Pieterse et al., 1994). MIS, which consists of 5–10 min of stage-tailored personal counseling combined with self-help guidance, is based on the Health Counseling model, a model developed as a specific tool helping health care providers to prepare patients for and assist them in the process of behavioral change (Gerards and Hospers, 1991; Gerards, 1993, 1997).
Although several studies have reported on the efficacy of smoking cessation programs for cardiac inpatients (Rosal et al., 1998; Taylor et al., 1990; Ockene et al., 1992; Rigotti et al., 1994; Johnson et al., 1999) and for hospitalized patients in general (Sirota et al., 1985; Stretcher et al., 1985; Orleans et al., 1990; Taylor et al., 1996; Miller et al., 1997; Rigotti et al., 1997), this mainly concerned interventions involving at least 1 h in-hospital counseling, combined with intensive follow-up contacts by telephone after discharge. The intervention in the current study, however, involved a minimal approach, tested under typical practice conditions.
In addition to the effectiveness study, a process evaluation was conducted to assess the fidelity of the delivery of the intervention by measuring the level of utilization of the intervention and the quality of its implementation. Process evaluations facilitate understanding why interventions were successful or failed. Moreover, their results can be viewed as accumulating evidence together with the results of the effectiveness evaluation. This combination of evidence indicators is referred to as data triangulation, which is especially important in quasi-experimental effectiveness studies (Green and Kreuter, 1991; Windsor et al., 1994; MacDonald and Muir, 1996; Tones, 1997; Nutbeam, 1998, 1999).
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Methods |
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Design, study population and procedure
Twenty-one hospitals were approached for participation in the study by contacting the managers of the cardiac wards. Ten hospitals refused to participate for various reasons, including a merger of wards, current participation in other time-consuming studies, staff turnover and personnel shortage. Initially, the remaining 11 hospitals were selected for random assignment to the intervention or control group. However, two hospitals only wanted to serve as controls. Similarly, two other hospitals were willing to cooperate only if they were included in the intervention group. This situation resulted in self-selected assignment of four hospitals and random assignment of the remaining seven hospitals, which meant a pre-test–post-test quasi-experimental design ex post (Rossi and Freeman, 1993
). Five hospitals constituted the intervention group, in which patients were assisted by means of the C-MIS. Six other hospitals served as the control group, in which patients received usual care. Patients nested in hospitals were the unit of analysis. From November 1995 to May 1997, smoking patients admitted for CHD to the cardiac wards of the selected hospitals were recruited by ward nurses. Patients who reported having smoked at least one cigarette in the 7 days prior to admission and were not in a life-threatening condition or in a terminal phase were eligible for inclusion. During the enrollment period, patients' smoking behavior in the 7 days prior to admission were routinely assessed by nurses at the intake. For emergency admission, the patient's smoking behavior was assessed later on, but within 96 h from admission. The two other criteria were also judged by nurses. Every day during the briefing at shift change it was communicated whether a patient was eligible for study inclusion or whether the smoking behavior of a patient still needed to be assessed. Ward representatives coordinated and supervised the process of inclusion. Ward representatives and nurses were explicitly instructed to ask all patients who were eligible for inclusion and to register refusals. Patients were informed about the study by means of a letter provided by ward nurses and were asked to volunteer for the study, including the possibility of being a control group member. Patients who were willing to participate had to give informed consent.
Baseline measures were obtained by means of a questionnaire administered by ward nurses within a few hours of the patients signing the informed consent. Outcome measures were assessed by means of questionnaires mailed to patients' home addresses 3 months after inclusion. Postal reminders were sent 3 and 8 weeks after the mailing of the questionnaire. If no response occurred, patients were phoned up by the researcher with the request to return the questionnaire.
Intervention
The MIS served as a blueprint for the intervention used in the present study. A few alterations were, however, made for the target population. The first was the inclusion of a stop-smoking advice by the cardiologist, which has been found to be essential for cardiac inpatients (Burling et al., 1984; Orleans et al., 1990; Miller, 1993; Orleans and Ockene, 1993; Fowler, 1997). The second alteration concerned the aftercare, which is not structurally embedded in MIS. In the C-MIS, it was embedded in the patient's check-up visit at the cardiology outpatient clinic, 4–6 weeks after discharge since a large proportion of cardiac inpatients are known to relapse after discharge (Breteler et al., 1988; Kottke et al., 1988; Orleans, et al., 1990; Taylor, et al., 1990; Rigotti, et al., 1991).
The final protocol consisted of the following (Figure 1). Firstly, patients received stop-smoking advice from their cardiologists. Secondly, a ward nurse assessed the patients' smoking behavior, their degree of addiction and their motivation to quit. This `readiness for change' formed the base of further counseling provided by nurses. Step 3 was only employed if a patient was unmotivated to quit: the nurse focussed on the positive and negative consequences of smoking cessation by means of strategies derived from motivational interviewing (Miller and Rollnick, 1991). If patients were already motivated to quit, nurses could proceed to Step 4: addressing the perceived barriers (expected problems and high-risk situations) and perceived self-efficacy expectations for smoking cessation. The nurse helped the patient select problem areas (e.g. withdrawal symptoms, stress, mood states). Subsequently, the patient was encouraged to consider what would work to cope and was helped to develop coping strategies. If a patient was motivated to quit and prepared to overcome high-risk situations, the nurse could proceed to Step 5: encouraging the patient to set a date for quitting. Depending on the situation, nurses could complete the Steps 2–5 in one or more (short) conversations. Before the patient's discharge from hospital, the nurse discussed the patient's progress and experiences so far. After discharge, the cardiologist addressed the patients' smoking behavior again at the cardiology outpatient clinic, to prevent relapse or to motivate a patient to make (another) attempt to quit. To remind the cardiologist, patients' hospital charts were stamped with a prompt and included a short report on the content of the in-hospital part of the intervention (on a so-called intervention card). In addition, a copy of the intervention card and a letter in which the protocol was explained were sent to the patient's general practitioner. In the letter the general practitioner was asked to pay attention to the patient's smoking behavior if visiting the general practice after hospital discharge.
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Patients also received a self-help manual and a brochure to read in the hospital and to take home. The self-help manual was partly based on the American Lung Association's `Freedom From Smoking' guide (Strecher et al., 1989
), structured in the same way as the protocol, and pre-tested and evaluated in two Dutch projects (Mudde et al., 1994; Willemsen and De Vries, 1995). The brochure focused on the relationship between smoking and the progression of CHD. In the case of more severe nicotine addiction or if a patient preferred intensive treatment, nurses pointed out possibilities to participate in a smoking-cessation group program after hospitalization at a cost of $45. Initially, the protocol also included a telephone follow-up by nurses 2 weeks after discharge from hospital. Ultimately, ward managers refused to include this due to time constraints. Patients of the control group received usual care, which consisted of occasional attention to their smoking behavior. There was no organized intervention.
Training on C-MIS
All the nurses in the intervention group received a standardized 2-h training. The training included information on the rationale of and the theory behind the intervention. The protocol was explained and practiced in role-plays. In addition, every ward received a training manual with instructions and a poster with a description of the protocol, while every nurse got a pocket-size reminder chart including an overview of the protocol and standardized messages on the pros of quitting and how to cope with high-risk situations. To ensure quality control, each ward appointed two representatives who supervised the interventions and to whom nurses could turn with questions. Moreover, meetings between the representatives and the researcher were held every 3 months to discuss progress, difficulties and experiences. Although cardiologists were not specifically trained for their part of the intervention, they received instructions from the ward representatives, a letter in which the protocol was explained, and a flow-chart with a description of the protocol and brief phase-related instructions.
Measurements
At follow-up, experimental patients' exposure to the intervention components (process evaluation) was assessed by asking whether the patient had talked with the nurse (during hospitalization) and the cardiologist (at the outpatient clinic) about smoking cessation, and whether they had received and read the self-help materials. The latter was assessed separately for both materials by asking: `To what extent did you read the..?' [answer scale ranging from `not read it' (1) to `read it all' (10)]. Questions referring to the personal counseling included: `Has the nurse spoken with you about smoking cessation during your hospital stay?'(yes/no) and `Has the cardiologist assessed your smoking habits at the outpatient clinic visit?' (yes/no). Furthermore, experimental patients were asked whether they had perceived more pros and less cons after the conversation with the nurse, whether they had learned how to cope with difficult situations and how to obtain social support [answer scale ranging from `not at all' (1) to `to a large extent' (10)]. Process evaluation questions were derived from program exposure measurements in earlier Dutch smoking intervention studies (Mudde et al., 1995; Dijkstra et al., 1998; Willemsen et al., 1998). To obtain the patients' evaluation of the intervention, patients in the intervention group were asked to rate the in-hospital and outpatient clinic parts of the intervention separately on an evaluation scale from poor (1) to excellent (10).
To assess whether patients in the intervention group had experienced greater attention for their smoking behavior than patients in the control group, the latter were also asked whether they had spoken about smoking with the cardiologist and the nurse. Patients in both groups were furthermore asked whether the conversations with these two types of health care providers had motivated them to quit or to sustain their attempt to quit. An example of such a question is: `Has the conversation with the nurse motivated you to make an attempt to quit?' [answer scale ranging from `not at all' (1) to `to a large extent' (10)].
The primary outcome measurement on intervention effectiveness was self-reported point prevalence abstinence [`Have you smoked during the last 7 days, even only one puff?' (yes/no)]. The secondary outcome was self-reported continuous abstinence (no smoking since hospital discharge).
At baseline, nurses documented the patients' reason for admission according the following categories: myocardial infarction, angina pectoris, decompensatio cordis, dysrhythmias, coronary angioplasty and a remaining category `other'.
The baseline questionnaire that patients had to complete assessed prior hospital admission for cardiovascular disease (CVD), Fagerström Test for Nicotine Dependence (FTND) (Heatherton et al., 1991), sociodemographics (age, gender and educational level), motivational phases of behavioral change and proximal cognitions [attitude toward quitting, social support for quitting and perceived smoking behavior in the environment (modeling), self-efficacy expectations, intention to quit].
The proximal cognitions were measured according to the ASE (Attitude–Social influence–self-Efficacy) model of behavioral determinants, a cognitive model which is commonly used to understand and predict health behavior (De Vries et al., 1988; Kok et al., 1991), and is quite similar to the Theory of Planned Behavior (Ajzen, 1991; Godin and Kok, 1996). Reliability of all cognitive scales was sufficient (Cronbach's 
> 0.60) and has been reported elsewhere (Bolman and De Vries, 1998).
Motivational phases were assessed by using an adaptation of the Prochaska and Diclemente Stage of Change (SoC) typology (Prochaska and DiClemente, 1992; Prochaska et al., 1992). In the current paper, stages are referred to as phases of change, because the term may be used inappropriately within the SoC concept. The reason is that a genuine stage theory has several characteristics, such as non-reversibility and invariant sequence, which are not met in the SoC concept (Bandura, 1997). Three alterations to the original typology were necessary to make it fit the situation of cardiac inpatients. First, there were no patients in the maintenance phase, because we only included patients who had smoked in the week prior to admission. Second, patients in the action phase were divided into patients situated in internal or external motivational phases, since patients could have been smoke-free at the time of measurement because they wanted to be, but also because of ward regulations or physical restraints at the time. (Although smoking in wards is prohibited by law, it is permitted to designate smoking areas within wards, e.g. in recreation rooms or in day rooms. Hospitals may also impose a total smoking ban. Because Dutch hospitals and wards may differ in their non-smoking policy, patients in some wards may have been allowed to smoke, whereas others were not.) A previous study among cardiac inpatients had suggested that this subdivision was necessary (Bolman and De Vries, 1998). Thirdly, patients in the preparation and contemplation phases were combined because of the small sample size of the latter (n = 11). This resulted in four groups at baseline:
- Smokers in precontemplation phase: had been smoking since admission and were not planning to quit within 6 months.
- Smokers in contemplation phase: had been smoking since admission and were planning to quit within 6 months.
- Patients in external motivation phase: had not been smoking since admission, but intended to start smoking again as soon as possible.
- Patients in internal motivation phase: had not been smoking since admission and were planning to maintain non-smoking.
Analyses
Baseline differences between the two conditions were tested using 
2 statistics for the categorical and dichotomous variables (gender, educational level, prior admission for CVD, reason for admission, 24-h attempt to quit in the year prior to admission, motivational phase of change and type of hospital) and t-tests for the continuous variables (age, age of smoking initiation, FTND score, intention to quit, pros and cons of quitting, perceived self-efficacy, social support and modeling).
In order to determine whether selective dropout (dropouts were defined as those who did not return the follow-up questionnaire) had taken place during the follow-up period, attrition between pre-test and post-test was assessed by logistic regression analysis, using attrition as the dependent variable and condition and baseline characteristics as predictors.
The effectiveness of the intervention was tested by logistic regression analysis. Condition and covariates (age; gender; educational level; prior admission for CVD; reason for admission; FTND score; intention to quit; motivational phase; pros and cons of quitting; modeling; social support; self-efficacy; previous quit attempt; age of smoking initiation; type of hospital) were the independent variables. Covariates were always included to correct for baseline differences and to increase the statistical power by reducing unexplained variance (Robinson and Jewell, 1991). Based on previous research among CHD patients (Ockene et al., 1992; Rosal et al., 1998), interactions between (1) reason for admission and condition, and (2) motivational phase and condition were tested. Condition and the covariates were entered first as one block, followed by the interaction terms. Interaction terms were then removed one by one (P < 0.10), using a hierarchical backward elimination procedure. Because the intervention was supposed to be superior to usual care (i.e. among others this was based on the results obtained with the MIS), a one-sided test was used to test the intervention effect. As regards the covariates, two-tailed tests were used since the literature was ambiguous about the influence of these factors. Furthermore, since four of the 11 hospitals had selected their own treatment instead of being randomized to the experimental or control condition, an indicator of self-selection of treatment (yes/no) was constructed. The final logistic regression models were re-run with this indicator and its interaction with treatment included as predictors to check whether the self-selection had influenced the treatment effect or the smoking outcomes.
Logistic regression analysis assumes that the outcomes are statistically independent. However, our design was a nested design, with patients nested under hospitals, which may have led to intra-class correlation (i.e. outcomes in the same hospital are related due to hospital effects on the outcome). Since entire hospitals, rather than individual patients within hospitals, were assigned to treatment conditions, ignoring intra-class correlation would lead to underestimation of the standard error of the treatment effect, too narrow confidence intervals and possibly to type 1 errors (Bryk and Raudenbusch, 1993; Goldstein, 1995; Longford, 1995). We therefore re-ran our final logistic regression models with mixed effect logistic regression using EGRET version 1.02.10 (Statistics and Epidemiology Research, 1993), treating patients nested within hospitals and hospitals as random effects.
Sample size
Based on previous research, it was assumed that 40% of the control patients would quit, against 50% in the intervention group. For a significance level of 0.05 (one-tailed) and a power of 80%, this implied a sample size of 650 patients. Assuming 20% dropouts, the sample needed to include 815 smoking patients at baseline.
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Results |
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Response and attrition analysis
From November 1995 to May 1997, 891 hospitalized smokers were identified. Thirty-eight patients (4%) refused to participate. Reasons for refusal were not obtained since medical/ethical policies did not allow this. Furthermore, 64 patients (8%) had to be excluded because 30% or more of the baseline questionnaire had not been filled in. Of the remaining patients (n = 789), 401 (51%) were in the control group and 388 (49%) belonged to the intervention group (Figure 2
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At the post-test, 10 patients (2%) in the intervention group and eight patients (2%) in the control group were deceased and therefore excluded from the analyses. Two control patients were too ill to fill in the questionnaire and were also excluded. Eighty-seven (23%) patients in the intervention group and 84 (21%) in the control group were lost to follow-up. In sum, from pre-test to post-test 78% (n = 598) of the remaining 769 responders were reached (Figure 2
). Logistic regression analysis on attrition revealed that dropouts were more often from the intervention group [OR = 1.55, 95% confidence interval (CI) = 1.04–2.29, P < 0.05], perceived more pros of quitting (OR = 1.52, CI = 1.06–2.19, P < 0.05), had weaker intentions not to smoke after hospital discharge (OR = 0.91, CI = 0.85–0.99, P < 0.05), perceived fewer non-smokers in their direct environment (OR = 0.48, CI = 0.30–0.78, P < 0.05) and were less often in the internal motivation phase (OR = 0.33, CI = 0.15–0.73, P < 0.05).
Comparison of groups at baseline
As can be seen in Table I, the intervention group contained significantly more patients with a lower level of education, fewer patients who had been admitted earlier for CVD, more patients admitted for a myocardial infarction and less patients admitted for the category `other' than the control group. Patients in the intervention group also reported significantly stronger intentions to quit smoking, reported more positive consequences of quitting, perceived more social support and were more often in the internally motivated action phase.
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Process evaluation
With respect to the degree of patient exposure to the intervention components, the process evaluation among intervention patients revealed that 76% of the patients had received the self-help manual, 65% had received the brochure, 84% reported having spoken about smoking cessation with the nurse during their hospitalization and 75% reported that the cardiologist had assessed their smoking behavior during the aftercare. Patients in the intervention group reported that the conversation(s) with the nurse had helped them to perceive more pros and fewer cons of quitting [M = 7.0; SD = 2.89; scale range: 1 (not at all) to 10 (to a large extent)]. As regards the extent to which the conversation had enabled patients to cope with high-risk situations and to obtain support in their immediate environment (similar answer scales were used), patients were less positive, with average scores of 5.7 (SD = 3) and 5.9 (SD = 2.99), respectively. Self-help materials were read moderately well: patients scored averages of 6.39 (SD = 3.64) and 6.23 (SD = 3.85) for the self-help guide and brochure, respectively. Intervention patients also rated their appreciation for the way the issue of smoking had received attention during admission and after discharge. The in-hospital attention was given an average score of 7.78 (SD = 2.68), while the aftercare was given a 6.57 (SD = 3.35).
Compared to control patients, Table II shows that patients of the intervention group indicated significantly more often that nurses and cardiologists had addressed their smoking behavior. They furthermore indicated significantly stronger that the conversations with the nurse had motivated them to make an attempt to quit and had made it easier to sustain such an attempt. The same was reported about the conversation with the cardiologist during the aftercare.
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Effectiveness of C-MIS
An `intention-to-treat' procedure treating dropouts as failures, i.e. as post-test smokers, is often recommended to evaluate treatment effects because it is not affected by self-selection issues (Lichtenstein and Glasgow, 1992
; Lando, 1993; Hajek, 1994; Windsor et al., 1998). This option might, however, be too conservative in studies with high dropout rates. Therefore, and in line with several other studies among cardiac inpatients, we performed one analysis without dropouts and one with dropouts regarded as smokers (Taylor, et al., 1990; Rigotti et al., 1994).
Logistic regression analysis excluding dropouts revealed no interaction effects (P > 0.25). Table III shows the final logistic regression model with a significant intervention effect on point prevalence abstinence (OR = 2.11, 90% CI = 1.50–2.98, P < 0.001, one-tailed). The unadjusted OR for the intervention effect was slightly higher (OR = 2.48, 90% CI = 1.76–3.50, P < 0.001, not presented in Table III). Point prevalence abstinence was furthermore significantly associated with the following baseline variables (Table III): being an internally motivated actor, having high self-efficacy expectations, being admitted for a myocardial infarction and making a first attempt to quit. With regard to continuous abstinence, no interaction effects were found either (P > 0.79). As Table IV shows, a significant intervention effect was found (OR = 1.41, 90% CI = 1.02–1.95, P < 0.05, one-tailed) in the regression model adjusted for covariates. Again, the unadjusted OR for the intervention effect was higher (OR = 1.95, 90% CI = 1.45–2.61, P < 0.001, not presented in the table). Continuous abstinence (Table IV) was associated with not having been admitted for CVD before (P < 0.05) and with being an internally motivated actor (P < 0.001).
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Logistic regression analysis according to the intention-to-treat procedure and treating dropouts as smokers also revealed no interaction effects on both outcomes (P > 0.41). A significant intervention effect on point prevalence abstinence (OR = 1.35, 90% CI = 1.01–1.81, P < 0.05, one-tailed) was found if covariates were included (Table III
). The unadjusted OR for intervention effect was 1.95 (90% CI = 1.45–2.61, P < 0.001, not presented in Table III). Covariates associated with point prevalence abstinence were similar to those found in the analysis excluding dropouts, with the exception of a significant association between modeling and the outcome and intention and the outcome. For continuous abstinence (Table IV), no significant intervention effect was found if covariates were included (OR = 1.05, 90% CI = 0.78–1.40, P = 0.40, one-tailed). The unadjusted OR was, however, significant (OR = 1.65, 90% CI = 1.23–2.22, P < 0.001, not presented in Table IV). Effects of covariates were similar to those in the analysis without dropouts, except for the significant associations of the outcome with intention and modeling. Forced entry of the indicator for self-selection of treatment condition by the hospital at hand and its interaction with treatment into the final models (see Methods) suggested that self-selection had neither influenced the treatment effects (as interaction effects; P > 0.43) nor influenced the smoking outcomes (as main effects; P > 0.22 after eliminating the interaction from the model). Magnitude and significance of the treatment effects were not substantially different from the regression analyses without the indicator for self-selection included.
A check of the assumptions for logistic regression gave satisfactory results for all outcome variables reported. Comparison of the logistic regression output with re-analysis of the final models using random effect logistic regression in EGRET (Statistics and Epidemiology Research, 1993) did not show random hospital effects for the outcome variables (all P > 0.21). Magnitude and significance of the treatment effects were comparable to those obtained in SPSS.
Detailed insight into the quitting behavior in each individual hospital can be derived from Table V, which shows that the intervention hospitals generally showed higher point prevalence and continuous abstinence cessation rates than the control hospitals, though the differences were substantially smaller in the intention-to-treat analysis.
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Discussion |
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The process evaluation data on program exposure showed that most patients in the intervention group had indeed received the intervention. Patients in this group also reported that the conversations with the nurse had motivated them to quit smoking. They were, however, less positive about the guidance they had experienced regarding social support and coping, which suggests that nurses need to improve their performance in this respect. Previous studies also reported that nurses experienced difficulties in helping patients to cope with high-risk situations (Kviz et al., 1995
; Nagle et al., 1999). Therefore, it seems desirable to improve the nurses' training, e.g. by supplementing it with feedback sessions to review and improve skills acquisition. Several studies (Taylor et al., 1990; Ockene et al., 1992; Miller et al., 1997) have suggested that nurses' training should include follow-up, which was not possible in the present study due to financial and time constraints. Significant intervention effects were found on both outcomes when dropouts were not included. However, the intention-to-treat analyses, which included dropouts as smokers, only showed a significant effect on point prevalence abstinence. These results were probably not distorted by baseline differences, nor by possible covariates, since they were accommodated for by including them in the regression model. Evidence that no distortion was introduced can also be found in the fact that the unadjusted ORs for the intervention effect were higher and significant for all outcomes. No evidence was found that the differences in the randomization procedure, resulting in self-selection by four of the 11 hospitals, influenced the treatment effect (as an interaction effect) or the smoking cessation outcomes (as a main effect). Furthermore, the random effect logistic regression analyses did not show a random hospital effect and confirmed the results of the SPSS analyses. Intervention effects were not modified by the two patient characteristics that were suspected to interact with treatment, since interactions were absent.
In sum, considering the intention-to-treat results as the most appropriate to evaluate the effectiveness (due to the substantial dropout rate and its relation to treatment and some baseline characteristics), it can be concluded that the intervention produced a small but significant intervention effect on point prevalence abstinence. It is conceivable that greater effects can be reached. The present results were obtained under conditions with moderate intervention coverage. Moreover, nurses' efforts in helping patients to obtain social support and to cope with high-risk situations were not always successfully employed. Finally, the intention-to-treat results reflect the most conservative effect estimation.
In contrast to our intention-to-treat intervention effects, three other studies among cardiac inpatients failed to find significant differences in (intention-to-treat) point prevalence abstinence after 4 (Rigotti et al., 1994) and 6 months (Orleans et al., 1990; Johnson et al., 1999). Ockene and colleagues, however, reported intervention effects on (intention-to-treat) point prevalence abstinence that were comparable to those found in the present study, though they were measured after 6 months and only for patients admitted with severe myocardial infarction (Ockene et al., 1992). Two other studies reported stronger (intention-to-treat) intervention effects than those found in the present study, using 1-year follow-up measurements (Taylor et al., 1990; Miller et al., 1997). Taylor's study, however, concerned only myocardial infarction patients, whereas our intervention also aimed at patients admitted for less severe complaints such as angina pectoris, who are less likely to quit smoking than myocardial infarction patients (Ockene et al., 1992; Van Berkel et al., 1999). All other studies referred to here involved more extensive interventions than ours. Furthermore, the ORs we found were comparable to those reported in the Cochrane Review on the efficacy of nurse-delivered interventions in general (Rice and Stead, 1999). This review, however, only included randomized trials with a follow-up period of at least 6 months. Our results were also comparable to the 12-month effects of the MIS, on which our intervention was based (Pieterse et al., 1994; Pieterse, 1999).
Our process evaluation revealed that the implementation of the protocol and the training of nurses need to be improved, as does the protocol used. Miller and colleagues found that repeated telephone support (four calls) after discharge increased the cessation rate significantly after 1 year (Miller et al., 1997). Hence, we would recommend intensifying the aftercare with several follow-up telephone calls. Furthermore, we agree with recommendations to include nicotine replacement therapy as a formal aid in future interventions for cardiac patients (Fiore et al., 2000a,b); this was not included in the intervention in the present study. Finally, disease-prone personality factors such as state-anxiety and depressive symptoms, which often characterize the target population (Huijbrechts et al., 1996; McKenna and Higgens, 1997; Hemingway and Marmot, 1999), may need greater attention in the intervention. CHD patients with anxiety and depressive feelings have shown greater persistence with regard to smoking (Huijbrechts et al., 1996). Although it is a challenge to intervene successfully on these factors in a minimal intervention like that used in the present study, efforts have to be made to find out how smoking patients who suffer from psychological problems can be approached successfully by using an additional counseling module for this group.
In line with previous findings (Orleans et al., 1990; Taylor et al., 1990; Glasgow et al., 1991; Ockene et al., 1992; Rigotti et al., 1994; Rosal et al., 1998), smoking cessation was associated with the reason for admission, previous admission for CVD, intention to quit, modeling, self-efficacy and the motivational phase that patients were in at the pre-test.
The present study is subject to a number of limitations. First, although a full randomized control trial was planned at the start of our study in order to strengthen the internal validity of the study (Murray et al., 1989) and to avoid between-group contamination (Sackett et al., 1988), the randomization procedure failed for four hospitals. In-depth analyses showed, however, that similar treatment effects were found for patients in the self-selected hospitals and the randomized hospitals. Second, attrition was high and selectivity occurred. Because the selectivity concerned treatment condition and baseline characteristics which were also independently related with smoking cessation, the effects found in the analyses without dropouts might have been overestimated. The selective dropout may also have lowered the external validity. The high attrition rate was partly caused by patients changing their home addresses without informing us. Utilization of a tracking system based on hospital records (which was not done in the present study) is therefore recommended. Telephone follow-up assessments are also recommended, since this procedure may result in attrition rates of 10% or less (Ockene et al., 1992; Rigotti et al., 1994; Taylor et al., 1996; Miller et al., 1997). Third, despite our efforts to obtain a representative sample of smoking cardiac inpatients, the long period needed to include sufficient numbers of patients suggests that not all smoking patients were approached. Nurses confirmed this, mentioning time constraints and forgetfulness as the most important causes. Hence, the patient sample may not be representative.
Fourth, no procedures were used to validate self-reported smoking behavior. Patients may have under-reported or falsely reported their smoking behavior. However, several intervention studies in the general population (Kottke et al., 1988; Glasgow et al., 1993; Murray et al., 1993) as well as among CHD patients (Taylor et al., 1990; Ockene et al., 1992; Miller et al., 1997; Berkel et al., 2001) have reported that treatment groups are not more likely to misrepresent their smoking behavior than controls. Therefore, we assume that any bias that may have occurred did not significantly affect the differences found between the groups. Moreover, some researchers (Hansen et al., 1985; Lichtenstein and Glasgow, 1992) have reported that self-reports are accurate when anonymity and confidentiality are assured and an identification coding system is used, which was the case in the present study. Biochemically validated studies among patients with coronary artery diseases found that self-reports were valid for this specific population (Sirota et al., 1985; Rice et al., 1994).
A fifth limitation concerns the power of the study. It is unclear whether the study had enough power to detect interactions in the regression analysis, since we did not include them in our power calculations. Furthermore, when planning the sample size of the study, the nesting of patients within hospitals was ignored. This may have led to an underestimation of the standard error of the treatment effect and thereby also of the sample size needed. However, the data analysis showed neither hospital effects nor underestimation in analyses that ignored the nesting.
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Acknowledgments |
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This study was made possible through the collaboration of the following Dutch hospitals: University Hospital Maastricht, University Hospital Rotterdam, University Hospital Leiden, Rijnland Hospital, Rijnstate Hospital, De Heel Hospital, OLVG Hospital, Bosch Medical Centre, St Franciscus Hospital, Westfries Hospital and Medical Centre Alkmaar. The authors would also like to thank the nurses at these hospitals and the patients who participated in the present study. Medical ethics committees of all the participating hospitals gave permission for the present study and patients who were willing to participate gave their informed consent. This study was supported by grants from The Netherlands Heart Foundation and The Dutch Foundation on Smoking and Health. At the time of the study, C. B. was working at Maastricht University
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