Evaluation of the mood and physical symptoms scale (MPSS) to assess cigarette withdrawal

Transcription

1 Psychopharmacology (2004) 177: DOI /s ORIGINAL INVESTIGATION Robert West. Peter Hajek Evaluation of the mood and physical symptoms scale (MPSS) to assess cigarette withdrawal Received: 5 February 2004 / Accepted: 26 April 2004 / Published online: 4 June 2004 # Springer-Verlag 2004 Abstract Rationale: The mood and physical symptoms scale (MPSS) was developed in the early 1980s to assess cigarette withdrawal symptoms, and variants of it have been used for 20 years. To date, no paper has been published on the properties of the scale. Objectives: To evaluate psychometric properties of MPSS and the interrelationship between the key tobacco withdrawal symptoms. Methods: The core elements of the MPSS involve 5-point ratings of depressed mood, irritability, restlessness, difficulty concentrating and hunger and 6- point ratings of strength of urges to smoke and time spent with these urges. The data set chosen for analysis was well suited to the task in that it involved a relatively large sample, abstinence was defined as not a puff for 24 h biochemically verified, participants were not using any medication that would have reduced withdrawal discomfort (e.g. nicotine patch), the abstinence rate was very high resulting in minimal bias due to attrition, and ratings were provided on three occasions prior to abstinence. The study involved 111 smokers setting a target quit date of whom 106 attempted abstinence and 96 achieved it. Results: The MPSS items were stable prior to abstinence and sensitive to abstinence. Post-abstinence increases in mood and physical symptoms demonstrated a high level of internal coherence. Ratings of urges to smoke correlated highly with changes in mood and other symptoms. Ratings of hunger correlated less well with the scale as a whole and may involve some distinct processes. Conclusions: The MPSS meets the key requirements of a cigarette withdrawal scale. Although urge to smoke/craving was not R. West (*) Cancer Research UK Health Behaviour Unit, Department of Epidemiology and Public Health, University College London, London, WC1E 6BT, UK robert.west@ucl.ac.uk P. Hajek Barts and the London School of Medicine and Dentistry, Queen Mary s School of Medicine, London, UK included in the list of DSM-IV withdrawal symptoms, it should be regarded as forming part of the withdrawal syndrome. Keywords Cigarette. Withdrawal. Nicotine. Smoking. Measurement. Symptom. MPSS Introduction Abstinence from smoking results in a range of psychological and physical changes, some of which simply represent a return to non-smoking state (offset effects) while others reflect a temporary period of re-adjustment to loss of nicotine to which the smoker s body has become accustomed (Hughes et al. 1990). There are several selfreport questionnaires in widespread use that aim to quantify these changes (see Schneider et al. 1983; Hughes and Hatsukami 1986; Welsch et al. 1999; Shiffman et al. 2000b; Shiffman et al. 2004). These measures differ in the symptoms included, the number of items and wording used to describe the symptoms and the response formats (Patten and Martin 1996). One such scale was developed in the early 1980s and first used in a study examining the effects of nicotine gum on withdrawal symptom severity (West et al. 1984a). It was also used to study the effects of switching to a low nicotine cigarette (West et al. 1984b) and the effects of switching long-term nicotine gum users to placebo gum (West and Russell 1985). In one study, items in the scale were found to predict subsequent relapse (West et al. 1989). Variants of the scale have been found to detect effects of the nicotine inhalator (Hajek 1989) and the nicotine nasal spray (Sutherland et al. 1992) in placebocontrolled studies. The scale is now routinely used in many stop smoking services in England. The psychometric properties of this particular scale have not been reported. The aim of this paper is to assess the internal structure and responsiveness to abstinence of the core items of the scale covering the primary symptoms of cigarette withdrawal.

2 196 We used data from a randomised placebo-controlled trial of the 5-HT 3 antagonist, ondansetron. The drug was found to have no effect on abstinence or any symptoms of abstinence and no non-significant trends (P<0.1) were observed (West and Hajek 1996) but, probably because of a behavioural support programme that was in operation concurrently, the abstinence rate for the 24 h following the quit date was high (90%). The drug is used as an antiemetic; it was hoped that it may have anxiolytic and antipsychotic properties, but in the event this turned out not to be the case. Therefore, the study provided an opportunity to study withdrawal symptoms uncontaminated by medications such as nicotine replacement therapy with little opportunity for bias due to dropout. (If subjects resume smoking because of particular withdrawal symptoms, this could distort the findings.) Another important feature of this study was that this abstinence was lapse free; in many studies of withdrawal occasional lapses are allowed and there is a risk that this might influence some of the symptoms reported. Finally this study included multiple baseline measurements so that the stability of the assessment prior to abstinence could be established. If the baseline is unstable, this raises doubts about the specificity of the measure with regard to detecting abstinence effects. The core items of the MPSS include irritability, poor concentration, restlessness, depressed mood and hunger. Anxiety ratings have also been included because anxiety is listed in DSM-IV as a nicotine withdrawal symptom (APA 1995). However, we have previously reported that MPSS anxiety ratings and scores from the Spielberger state trait anxiety inventory (STAI) actually decreased in lapse-free abstinent smokers (West and Hajek 1997). It was also found that the anxiety rating in the MPSS performed very similarly to the full STAI and correlated highly with it. We have suggested that anxiety is not a general feature of cigarette withdrawal in smokers who are lapse free, but rather a response to a quit attempt that is only partially succeeding (Shiffman et al. 2004). It is also possible that there are cultural differences in the interpretation of anxiety items between the US and the UK smokers (Shiffman et al. 2004). A feature of the MPSS is that, except for urges to smoke, it uses only one item to assess each withdrawal symptom. This keeps the scale as brief as possible and makes it suitable for studies that involve minimal contact with smokers. It is of particular interest to note whether this compromises reliability and sensitivity to abstinence. Apart from assessing the response of the MPSS to abstinence and its internal coherence, this study provided an opportunity to examine an issue concerning the measurement of urges to smoke or cravings. Many studies assess craving by comparing ratings while smoking with ratings after a period of abstinence (Shiffman et al. 2000a). This sometimes leads to apparent anomalies where craving ratings actually fall during abstinence. The philosophy of the MPSS is based on the idea that craving ratings while smoking ad lib do not represent a mental state of desire or need because generally when a smoker feels this need he or she can satisfy it by smoking (although recently this has become less the case). Ratings of craving during ad lib smoking may reflect observation by smokers of their own smoking behaviour as much as any felt need or desire. This would be similar to individuals rating themselves as hungry because they notice that they have been eating more than usual rather than by introspecting. If that is the case, scores based on the change from baseline would be less meaningful than raw scores obtained after a period of abstinence. The merits of the two approaches could be assessed by comparing how the raw post-quit score versus the change in urge score correlate with other withdrawal measures (e.g. irritability) that have been assessed using change scores. It was predicted that the raw post-quit urge rating would correlate more closely with other measures of withdrawal than would change in urges from baseline. Materials and methods One hundred and eleven smokers taking part in a placebocontrolled randomised trial of the 5-HT 3 antagonist ondansetron attended a clinic (West and Hajek 1996). Smokers were eligible to take part if they wished to stop smoking permanently, fulfilled DSM-IIIR criteria for nicotine dependence, were aged years, smoked 15 or more cigarettes per day, were not suffering from a poorly controlled physical condition, using psychotropic medication, or suffering from a psychiatric disorder, or were pregnant or breastfeeding. One hundred and six smokers attended on the quit date. A total of 96 (90%) managed reported not-a-puff abstinence for 24 h, confirmed by expired air carbon monoxide concentration less than 10 ppm. This study reports data from these 96 smokers. We did not include subjects who failed to remain abstinent because those subjects could not logically be regarded as being in withdrawal. Table 1 shows the baseline characteristics of this sample. Participants received behavioural support according to a standard regimen (Hajek et al. 1989). The programme uses group support to bolster motivation to remain abstinent. No specific expectations were provided regarding withdrawal symptoms. The subjects attended the clinic 2 weeks and 1 week prior to the designated quit date, on the quit date just prior to onset of abstinence (which began at the start of the session), and then 24 h later. Attendance was in the early evening. On these occasions they completed the mood and physical symptoms scale (MPSS). The MPSS included Table 1 Baseline characteristics of participants n(n attempting abstinence) 96 (111) Mean (SD) age (years) 39.8 (9.29) Percent (n) male 41.7 (40) Mean (SD) cigs per day 25.2 (8.70) Percent (n) smoking within 5 min of waking 28.1 (27) Mean (SD) expired air CO (ppm) 19.9 (8.36)

3 197 urge to smoke items (see below) only on the first visit and after 24 h abstinence. The core items of the MPSS consist of five single-item ratings of depressed mood, irritability, restlessness, hunger, and poor concentration, all believed to be part of the nicotine withdrawal syndrome (see Appendix 1). Anxiety was also measured using a single rating and using the STAI, but as noted in the Introduction section, neither the MPSS rating nor the STAI showed an increase, so it could not be included as a withdrawal symptom (West and Hajek 1997). Individual withdrawal effects in the MPSS are assessed by examining the change from baseline for each rating. In addition an overall score is obtained by summing these change scores. All items are rated on a 5-point scale: not at all, slightly, somewhat, very, extremely. In addition to the five ratings described above, the MPSS includes 6-point ratings of strength of urges to smoke and of time spent with urges to smoke. These two aspects of urges to smoke were originally separated because of the possibility that they might reflect different processes. Results Table 2 shows the means and SD of the raw ratings at all time points. Repeated measures ANOVAs on the three baseline scores showed them to be stable. There were no significant differences across the three time points in any measure. For the remaining analyses, the ratings were averaged across the three occasions. Paired t-tests on the change from the mean baseline to the 24 h rating showed consistent increases on all items. The ratings of strength of urges and time spent with urges after 24 h of abstinence correlated highly with each other, R=0.78 (P<0.001). The correlation was sufficiently high that the two ratings could reasonably be combined into a single mean score for the purpose of subsequent analyses. To assess the relative merits of using urge scores based on difference from baseline or raw urge scores during abstinence, the correlation between these scores and other withdrawal symptoms (expressed as change from mean baseline to 24 h rating) were assessed. If, as expected, the raw scores correlated more closely with other withdrawal ratings, this would support the view that calculating difference scores adds rather than removes error variance. Table 3 shows that the raw urge scores correlated more closely with all other withdrawal ratings than the difference scores, and in the case of irritability and the total MPSS score (excluding urges), significantly so. By contrast, when we examined how closely the raw scores from the other items (irritability, depression, hunger, restlessness and difficulty concentrating) correlated with difference scores from the remaining ones, we found that where they were significantly different, they correlated less well than did the difference scores for those items. Thus, the change in depression correlated better with the change in irritability than did the raw, postcessation depression score (R=0.44 versus R=0.27, t=2.9, P<0.01); change in depression correlated more highly with change in restlessness than did raw depression score (R=0.38 versus R=0.20, t=3.01, P<0.01); change in restlessness correlated more highly with change in irritability than did raw restlessness scores (R=0.58 versus R=0.44, t=2.30, P<0.05); change in hunger correlated more highly with change in irritability than did raw hunger score (R=0.15 versus R= 0.02, t=2.42, P<0.05). Only one correlation was marginally significant in the opposite direction: change in irritability correlated less well with change in hunger than did raw irritability scores (R=0.15 versus R=0.27, t=2.00, P=0.05). The raw urge score was used in subsequent analyses. A principal components analysis (PCA) of the MPSS was Table 2 Mean (SD) MPSS ratings at all time points. W-x, xweeks before quit date; QD quit date; 24H 24 h post-quit a Raw score W-2 W-1 QD 24H (change from mean baseline) Depressed 1.4 (0.59) 1.5 (0.74) 1.6 (0.91) (0.91) (P=0.002) Irritable 1.6 (0.88) 1.6 (0.90) 1.8 (0.94) (1.16) (P<0.001) Restless 2.2 (1.06) 1.9 (1.07) 2.1 (1.14) (1.20) (P<0.001) Hungry 2.2 (1.12) 2.0 (0.94) 2.0 (1.12) (1.13) (P<0.001) Poor concentration 1.7 (0.88) 1.8 (0.95) 1.9 (0.97) (1.31) (P<0.001) Strength of urges 3.0 (1.17) 3.6 a (1.36) (P=0.001) Time spent with urges 3.1 (1.14) 3.7 a (1.31) (P=0.003) Urge total 3.1 (1.07) 3.7 a (1.26) (P=0.001) Table 3 Correlations between raw urge scores and difference scores with other MPSS items Difference between correlations involving a shared variable: *P<0.01 by Steiger z-score Raw urge score Depressed mood Irritability 0.43* 0.25 Restlessness Hunger Poor concentration MPSS total (excluding urges) 0.46* 0.24 Difference urge score

4 198 Table 4 Results from principal components analysis of MPSS items Items Factor loadings Depressed 0.66 Irritable 0.74 Restlessness 0.80 Hungry 0.49 Poor concentration 0.64 Urge to smoke 0.77 undertaken. PCA was chosen because it makes no assumptions about the distributions of the scores and seeks only to find a solution that maximises the variance accounted for by underlying dimensions. The variables entered were the difference scores for depressed mood, irritability, restlessness, hunger and difficult concentrating and the absolute score for the mean of the ratings of strength of urges to smoke and time spent with urges to smoke. The PCA yielded a single component accounting for 48% of the variance. Table 4 shows the factor loadings resulting from the analysis. All the factor loadings were high, except for hunger which was moderate. The coefficient alpha for the scale was 0.78, indicating a high degree of coherence overall. The total MPSS score followed a normal distribution with a mean of 6.5 and SD of Discussion The results show that the MPSS is sensitive to changes in individual mood and physical symptoms resulting from 24 h of abstinence, despite only using one rating per construct. They lend support to the inclusion of urges as a core symptom and the approach of the using postabstinence raw urge scores rather than differences from baseline. The withdrawal syndrome measured by the items was coherent, although hunger was potentially distinct. This paper only deals with the most basic form of the scale. Except, for the absence of anxiety, the items are all those listed in DSM-IV (APA 1995). Of the other commonly used scales it bears the closest resemblance to the Minnesota withdrawal scale, the main difference being that the latter includes more than one label to describe each rating scale (e.g. hunger/weight gain) (Hughes and Hatsukami 1986). More recently, there has been evidence that other physical symptoms should be added including constipation (Hajek et al. 2003), mouth ulcers and upper respiratory tract symptoms (Ussher et al. 2003). There is also evidence for sleep disturbance following smoking cessation (Wetter et al. 1995). Further research is under way to assess the properties of the scale with these additional items included. The MPSS uses urges to smoke instead of the term craving because it is felt that craving may be subject to more variable interpretation by respondents (Kozlowski and Wilkinson 1987). It is possible that different results would be obtained with different terminology; however, given that the concepts in this area are essentially socially determined (i.e. they mean what the community chooses them to mean because they are not directly observable entities), this raises the much larger question of what is the best conceptualisation of the constructs involved, which is then tied up with the measurement process. There is a widely used multi-item scale measuring a particular conceptualisation of craving (Tiffany and Drobes 1991). Although the psychometrics of this scale have been widely explored, surprisingly there have been no direct comparisons with simpler measures such as are used in the MPSS or other withdrawal scales (e.g. Hughes and Hatsukami 1986; Shiffman et al. 2000b). For example, there has been no direct comparison of the ability of the different scales to discriminate between interventions that reduce craving, or to predict relapse. The fact that there are several withdrawal scales in current use has advantages in terms of the gamut of constructs and formats that are being canvassed. However, it poses problems when it comes to interpreting the results of studies using the different measures. It would be helpful to have direct comparisons between the measures in terms of their basic psychometric properties. This would help potential users choose the scale that best suited their purposes. The finding that urge to smoke forms a core element of the syndrome removes one of the arguments which led to its exclusion from the DSM-IV list of nicotine withdrawal symptoms (see Hughes et al. 1990). The other main plank that it was not reduced by nicotine replacement therapies has also been found to be incorrect (West and Shiffman 2001). Therefore it makes sense to consider urges to smoke as integral to the withdrawal syndrome. Hunger, by contrast, is less well integrated and this is compounded by the fact that it lasts longer than other symptoms (Hughes et al. 1994). It remains possible that hunger is an offset effect as is weight gain, and not a withdrawal symptom in the conventional sense. This needs to be explored further. This study is limited in examining withdrawal only at one time point. The goal was to describe the psychometric properties of the scale at the point in time when withdrawal symptoms would be expected to peak and when bias due to drop out would be minimal. It would be highly desirable to extend period of studies of this kind with all or almost all the participants remaining abstinent. One way to do this would be to conduct such a study in a closed environment where there was no access to cigarettes or to take advantage of naturally occurring situations where individuals could not smoke for an extended period. This study did not examine re-test reliability, concurrent validity or predictive validity. As noted in the Introduction, studies have found the MPSS to be sensitive to interventions such as nicotine replacement therapy and to predict relapse. However, comparison with other withdrawal scales, observer ratings of mood and more objective markers of behaviour would be useful.

5 199 Appendix 1: Mood and physical symptoms scale (MPSS) Please show for each of the items how you have been feeling over the past 24 h (circle one number for each item). Not at all Slightly Somewhat Very Extremely Depressed Irritable Restless Hungry Poor concentration How much of have you felt the urge to smoke in the past 24 h? (circle one number). All the time Almost all A lot of the time Some of A little of Not at all How strong have the urges been? (circle one number). Extremely strong Very strong Strong Moderate Slight No urges The timescale referred to in the header to the scale can vary. Usually it is 24 h or 1 week. In this study, all questions were with reference to the past 24 h References APA (1995) Diagnostic and statistical manual of mental disorders, 4th edn. American Psychiatric Association, Washington D.C. Hajek P (1989) Withdrawal-oriented therapy for smokers. Br J Addict 84: Hajek P, Jarvis MJ, Belcher M, Sutherland G, Feyerabend C (1989) Effect of smoke-free cigarettes on 24 h cigarette withdrawal: a double-blind placebo-controlled study. Psychopharmacology 97: Hajek P, Gillison F, McRobbie H (2003) Stopping smoking can cause constipation. Addiction 98: Hughes JR, Hatsukami D (1986) Signs and symptoms of tobacco withdrawal. Arch Gen Psychiatry 43: Hughes JR, Higgins ST et al. (1990) Effects of abstinence from tobacco: a critical review. In: Vingilis ER (ed) Research advances in alcohol and drug problems. Plenum, New York, pp Hughes JR, Higgins ST, Bickel WK (1994) Nicotine withdrawal versus other drug withdrawal syndromes: similarities and dissimilarities. Addiction 89: Kozlowski LT, Wilkinson DA (1987) Use and misuse of the concept of craving by alcohol, tobacco, and drug researchers. Br J Addict 82:31 45 Patten CA, Martin JE (1996) Measuring tobacco withdrawal: a review of self-report questionnaires. J Subst Abuse 8: Schneider NG, Jarvik ME, Forsythe AB, Read LL, Elliott ML, Schweiger A (1983) Nicotine gum in smoking cessation: a placebo-controlled, double-blind trial. Addict Behav 8: Shiffman S, Johnston JA, Khayrallah M, Elash CA, Gwaltney CJ, Paty JA, Gnys M, Evoniuk G, DeVeaugh-Geiss J (2000a) The effect of bupropion on nicotine craving and withdrawal. Psychopharmacology 148:33 40 Shiffman S, Khayrallah M, Nowak R (2000b) Efficacy of the nicotine patch for relief of craving and withdrawal 7 10 weeks after cessation. Nicotine Tob Res 2: Shiffman S, West R et al. (2004) The assessment of tobacco craving and withdrawal in smoking cessation trials. Nicotine Tob Res (in press) Sutherland G, Stapleton JA, Russell MA, Jarvis MJ, Hajek P, Belcher M, Feyerabend C (1992) Randomised controlled trial of nasal nicotine spray in smoking cessation. Lancet 340: Tiffany ST, Drobes DJ (1991) The development and initial validation of a questionnaire on smoking urges. Br J Addict 86: Ussher M, West R, Steptoe A, McEwen A (2003) Increase in common cold symptoms and mouth ulcers following smoking cessation. Tob Control 12:86 88 Welsch SK, Smith SS, Wetter DW, Jorenby DE, Fiore MC, Baker TB (1999) Development and validation of the Wisconsin Smoking Withdrawal Scale. Exp Clin Psychopharmacol 7: West R, Hajek P (1996) Randomised controlled trial of ondansetron in smoking cessation. Psychopharmacology 126:95 96 West R, Hajek P (1997) What happens to anxiety levels on giving up smoking? Am J Psychiatry 154: West RJ, Russell MA (1985) Effects of withdrawal from long-term nicotine gum use. Psychol Med 15: West R, Shiffman S (2001) Effect of oral nicotine dosing forms on cigarette withdrawal symptoms and craving: a systematic review. Psychopharmacology 155: West RJ, Jarvis MJ, Russell MA, Carruthers ME, Feyerabend C (1984a) Effect of nicotine replacement on the cigarette withdrawal syndrome. Br J Addict 79: West RJ, Russell MA, Jarvis MJ, Feyerabend C (1984b) Does switching to an ultra-low nicotine cigarette induce nicotine withdrawal effects? Psychopharmacology 84: West RJ, Hajek P, Belcher M (1989) Severity of withdrawal symptoms as a predictor of outcome of an attempt to quit smoking. Psychol Med 19: Wetter DW, Fiore MC, Baker TB, Young TB(1995) Tobacco withdrawal and nicotine replacement influence objective measures of sleep. J Consult Clin Psychol 63: