1 Measuring craving in a clinical setting Robert West University College London Madrid October 2007

Outline ‘Craving’ and ‘subjective motivation to smoke’ (SMS) Why measure SMS? How to evaluate a measure of SMS Existing measures of SMS Comparative evaluation of these measures Conclusions

Simple truisms Smoking a cigarette after the target quit date results from the fact that, on an occasion when a cigarette is available, the motivation to smoke is stronger than the motivation to resist Motivation to smoke when cigarettes are not immediately available can also drive behaviour to obtain them

Terms relating to motivation Motivation –mental activity that energises and directs behaviour: encompasses conscious deliberation as well as habitual and instinctive reactions Desire –feeling of wanting or needing something Urge –feeling of being impelled to engage immediately in a particular action Craving –???

Craving: lay definitions ‘A consuming desire; yearning’ ( ‘An intense desire for some particular thing’ ( ‘an intense and prolonged desire; yearning or appetite, as for affection or a food or drug’ (

Craving: academic definitions Expectancies about positive outcomes or escape from or avoidance of negative outcomes Feelings of urges arising out of frustration of automatic impulses Need to escape from unpleasant withdrawal symptoms Physiological changes during abstinence

Kozlowski was right; I was wrong 1987: Use and misuse of the concept of craving by alcohol, tobacco, and drug researchers’, Br J of Addiction, 82, –The concept is used by academics ambiguously and to mean different things 1989: "Cravings" are ambiguous: ask about urges or desires, Addictive Behaviors, 14, –‘Despite the dictionary definition of "craving" (a strong desire), two studies indicate that a substantial percentage of persons with alcohol and drug problems use the word "craving" to mean any desire or urge, even a weak one, to use substances. Researchers and clinicians are advised to beware of this ambiguity of "craving" and to consider the conceptual status of "craving" in their work.’

Problems with the term craving Academic definitions are proposed without establishing that they are more useful than the lay definition Varying definitions are used Measures based on one definition are interpreted as though they measured another definition Most of the motivational theory underpinning the definitions is implicit and imprecise or explicit but only captures some aspects of motivation The Questionnaire on Smoking Urges (QSU) which is based on a particular non-lay definition is becoming a de facto standard even though it has not been evaluated against existing measures

Addressing the problem Use the term ‘subjective motivation’ to refer to the broad experience of motivation to engage in a particular activity and Subjective Motivation to Smoke (SMS) Use the term ‘craving’ when the measurement focuses on intense desire as in the lay definition

Broad strategy Evaluate the existing measures of SMS, using a range of indices of validity Adopt a parsimonious approach, staying with simple measures unless more complex measures are shown to be necessary Note: SMS relies on introspection and therefore can only assess aspects of motivation to smoke that can be experienced and reported using a common language

Why measure SMS in clinical settings? Clinical research –as a proxy for abstinence in trials aimed at assessing likely effectiveness of cessation aids –in order to determine the mechanism of action of cessation aids –in order to gain a fuller understanding of smoking behaviour and why people find it hard to stop Clinical practice –to assess prognosis –to provide information on which to adjust treatment and management

5 criteria for evaluating measures of SMS in clinical settings 1.How sensitive are they to abstinence? 2.How far do they give consistent results when purportedly measuring the same level of motivation on different occasions? 3.How sensitive are they to interventions that affect relapse rates? 4.How well do they predict relapse? 5.How resource intensive are they?

Existing scales Minnesota Nicotine Withdrawal Scale (MNWS) Shiffman craving scale (SCS) Wisconsin Smoking Withdrawal Scale (WSWS) Cigarette Withdrawal Scale (CWS) Mood and Physical Symptoms Scale (MPSS) Questionnaire on Smoking Urges (QSU) Single rating of craving Smoker Complaint Scale (Schneider)

MNWS (Hughes) Please show how you have been feeling today NoneSlightMildModerateSevere Desire or craving to smoke01234

Shiffman scale For each item below, please circle the number (1-10) that shows best how you have felt today. –Urge to smoke –Need to smoke –Crave a cigarette –Need a cigarette

WSWS (Welsch) Please show on each of the scales below how you have been feeling today Strongly disagree DisagreeFeel neutralAgreeStrongly agree I have frequent urges to smoke I have been bothered by the desire to smoke a cigarette I have thought about smoking a lot 01234

CWS (Etter) The following statements describe how you feel today. Please indicate how much you agree or disagree with each of these statements. Totally disagree Mostly disagree More or less agree Mostly agree Totally agree The only thing I can think about is smoking a cigarette I miss cigarettes terribly12345 I feel an irresistible need to smoke 12345

MPSS (West) How much of the time have you felt the urge to smoke today? All the time Almost all the time A lot of the time Some of the time A little of the time Not at all How strong have the urges been today? Extremely strong Very strongStrongModerateSlightNo urges

Brief QSU (Tiffany) 1: I have a desire for a cigarette right now 2: Nothing would be better than smoking a cigarette right now 3: If it were possible I would probably smoke now 4: I could control things better right now if I could smoke 5: All I want right now is a cigarette 6: I have an urge for a cigarette 7: A cigarette would taste good now 8: I would do almost anything for a cigarette now 9: Smoking would make me less depressed 10: I am going to smoke as soon as possible Strongly disagree NeutralStrongly agree Items in black are Factor 1 and items in blue are Factor 2

Craving rating How much have you craved cigarettes today? A great dealQuite a bitSomewhatA littleHardly at allNot at all

Study 1: Sensitivity to abstinence Methods –60 male and female smokers randomly allocated to ‘abstinence’ versus ‘continue smoking’ conditions (30 in each group) –SMS measures taken at baseline and after 24 hours –checked abstinence with expired air CO –measures were: QSU Factor 1, QSU Factor 2, QSU total, MPSS strength of urges, MPSS time spent with urges, MPSS total, MNWS, Shiffman scale, WSWS, CWS, ‘craving’ rating

Subject characteristics Mean (SD) age: 30 yrs (9.8) Mean (SD) cigs per day: 15 (6.1) Mean (SD) reported quit attempts in past 5 years: 1.9 (1.9)

Sensitivity to abstinence: analysis General linear model examining interaction between –time (baselines versus 24 h) and –group (continue smoking versus abstain) Calculate eta squared (variance accounted for) for each SMS measure Also calculate eta squared for prediction of 24 h score from baseline score

Sensitivity to abstinence: results All values are greater than zero at p<.0001

Consistency: analysis Select smokers who continued smoking Calculate correlation between 24 h score and baseline score for each measure

Consistency: results All values are greater than zero at p<.0001

Combining scales Used forward stepwise logistic regression to assess independent contribution of each scale to distinguishing between the abstinent and non-abstinent smokers QSU total score and MPSS total score made independent contributions but additional effect of adding one to the other was small

Study 2: Sensitivity to medications aiding cessation Methods –combined data from two phase 3 trials comparing varenicline, bupropion and placebo –1818 participants provided SMS data one week after the target quit date –examined the effect of varenicline versus bupropion versus placebo on SMS at this time point using baseline measurements as covariates –did this separately in abstinent and non-abstinent participants –used Brief QSU and the single ‘desire/craving’ rating from the MNWS –calculated t-values for pairwise comparisons with adjustment for multiple post-hoc comparison

Results t-values provide a comparable estimate of effect size; A=abstinent, NA=non-abstinent

Conclusions The term ‘craving’ is used in varying ways and operationalised differently in different measures The term ‘subjective motivation to smoke’ (SMS) might be more appropriate in research studies with ‘craving’ being reserved for ‘intense desire’ In terms of sensitivity to abstinence and consistency, single ratings or scales with two items appear to work as well as the Brief QSU with 10 items In terms of sensitivity to medications that affect abstinence and are believed to reduce the need to smoke a single rating of ‘desire/craving’ performs the same as the Brief QSU There seems to be nothing to be gained by using multi-item scales such as the Brief QSU and a range of shorter scales or single item ratings are available for measuring SMS There may be a small advantage to using the Brief QSU with the MPSS when there is a strong need to maximise precision but this needs to be tested further

‘Better fewer, but better’ V. I. Lenin

Thanks Study 1 was supervised by Dr Michael Ussher at St George’s, University of London The analysis for Study 2 was undertaken by Joseph Cappelleri and Andrew Bushmakin of Pfizer