Measurement properties of the Work Limitations Questionnaire were sufficient among cancer survivors

Abstract

The purpose of this study was to determine reproducibility, validity, and responsiveness of the Work Limitations Questionnaire (WLQ) among cancer survivors. A cohort of 53 cancer survivors completed the WLQ and other questionnaires at baseline, 4-week, and 6-month follow-up. We assessed internal consistency, intraclass correlation coefficient, standard error of measurement, floor- and ceiling effects and compared the WLQ with other constructs. For responsiveness, we assessed the following anchor-based measures: minimal important change (MIC) versus smallest detectable change (SDC) and area under the curve (AUC) of receiver operation characteristic (ROC). We found sufficient reproducibility at group level but not at individual level as the MIC (4.0) exceeded SDC at group level (3.1) but not at individual level (18.0). There was no indication of systematic bias or proportional bias. The internal consistency and construct validity for the WLQ and its subscales were sufficient or slightly less than sufficient. There was a floor effect for one subscale, but there were no ceiling effects. Responsiveness was sufficient with an AUC of a ROC of 0.65. The WLQ is reproducible, valid, and responsive for use at group level among cancer survivors but not sufficiently reproducible for use at individual level.