Evaluation of smoking-specific and generic quality of life measures in current and former smokers in Germany and the United States

Abstract

BackgroundHealth-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.MethodsTQOLIT™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.ResultsTests 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.ConclusionsGerman- 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.

Preliminary Evaluation of a New German Translated Tobacco Quality of Life Impact Tool to Discriminate Between Healthy Current and Former Smokers and to Explore the Effect of Switching Smokers to a Reduced Toxicant Prototype Cigarette

“…The significant correlations seen between smoking-specific measures and general measures in current smokers as compared to weaker correlations among former smokers support the validity of TQOLITv1 in measuring the effects of current smoking. The pattern of significant correlations at baseline between general and smoking-specific measures observed in this trial for the German translation is similar to the pattern observed for the English language version of TQOLITv1, 33 suggesting that the results regarding construct validity are generalizable.…”

Standardizing disease-specific quality of life measures across multiple chronic conditions: development and initial evaluation of the QOL Disease Impact Scale (QDIS®)

“…Although any self-report bias is unlikely to account for the superior discriminant validity observed for QDIS over generic measures, QDIS should be evaluated in relation to more objective clinical criteria, which are also likely to make interpretation guidelines more useful clinically. Examples of more independent clinical validation include a recent trial using QDIS with attribution to smoking; QDIS correlated substantially higher with four biomarkers of smoking exposure [ 78 ] and discriminated between current and former smokers much better [ 79 ] than generic SF-36v2® Health Survey measures. Similarly, QDIS with attribution to kidney disease discriminated across clinically-defined stages of CKD better than the SF-12 [ 65 ].…”

Assisted reproductive technology treatments and quality of life: a longitudinal study among subfertile women and men

“…Although a disease-specific questionnaire may provide more precise indications of the true impact of infertility [45], the use of a general questionnaire like the SF-36 provides an ultimately subjective evaluation of health-related QoL in general. The SF-36 is one of the most widely used questionnaires in the literature of infertility [41,46], and it is still currently considered one of the most reliable instruments for the assessment of health-related QoL, in both general and specific clinical populations [47][48][49], also within the perinatal period [50,51]. Therefore, the choice of this questionnaire may allow, for future researchers, to deepen the comparisons on QoL across different clinical populations.…”