Evaluation of smoking-specific and generic quality of life measures in current and former smokers in Germany and the United States.
BACKGROUND
Health-related quality of life (QOL) surveys include generic measures that enable comparisons across conditions and measures that focus more specifically on one disease or condition. We evaluated the psychometric properties of German- and English-language versions of survey scales representing both types of measures in samples of current and former smokers.


METHODS
TQOLIT(™)v1 integrates new measures of smoking-specific symptoms and QOL impact attributed to smoking with generic SF-36 Health Survey measures. For purposes of evaluation, cross-sectional data were analyzed for two independent samples. Disease-free (otherwise healthy) adults ages 23-55 used a tablet to complete surveys in a clinical trial in Germany (125 current and 54 former smokers). Online general population surveys were completed in the US by otherwise healthy current and former smokers (N = 149 and 110, respectively). Evaluations included psychometric tests of assumptions underlying scale construction and scoring, score distributions, and reliability. Tests of validity included cross-sectional correlations and analyses of variance based on a conceptual framework and hypotheses for groups differing in self-reported smoking behavior (current versus former smoker, cigarettes per day (CPD)) and severity of smoking symptoms in both samples and, in the German trial only, clinical parameters of biomarkers of exposure.


RESULTS
Tests of scaling assumptions and internal consistency reliability (alpha = 0.71-0.79) of the smoking-specific measures were satisfactory, although ceiling effects attenuated correlations for former smokers in both samples. Correlational evidence supporting validity of smoking-specific symptom and impact measures included their substantial inter-correlation and higher correlations (than generic measures) with smoking behavior (favoring former over current groups) and CPD in both samples. In the German trial, both smoking-specific measures correlated significantly (p < 0.05) with all four biomarkers. QOL impact attributed to smoking correlated with the SF-36 mental but not physical summary measures in both samples.


CONCLUSIONS
German- and English-language TQOLITv1 surveys have comparable and satisfactory psychometric properties. Cross-sectional tests, including correlations with four biomarkers, support the validity of the new smoking-specific measures for use in studies of otherwise healthy smokers. Smoking-specific measures consistently performed better than generic QOL measures in all tests of validity.
John Ware Research Group, 10 Wheeler Court, Watertown, MA, 02472, USA. john.ware@jwrginc.com.|Department of Quantitative Health Sciences, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA, 01655, USA. john.ware@jwrginc.com.
John E
JE
Ware
John Ware Research Group, 10 Wheeler Court, Watertown, MA, 02472, USA. barbara.gandek@jwrginc.com.|Department of Quantitative Health Sciences, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA, 01655, USA. barbara.gandek@jwrginc.com.
Barbara
B
Gandek
British American Tobacco (Investments) Ltd., Group Research & Development, Regents Park Road, Southampton, SO15 8TL, UK. dranu23@gmail.com.
Anuradha
A
Kulasekaran
John Ware Research Group, 10 Wheeler Court, Watertown, MA, 02472, USA. rick.guyer@jwrginc.com.
Rick
R
Guyer
D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D005858:Germany; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D011594:Psychometrics; D011788:Quality of Life / Q000523:psychology*; D015203:Reproducibility of Results; D057566:Self Report; D012907:Smoking / Q000523:psychology*; D014481:United States; D055815:Young Adult