Methods in Measuring Return to Work: A Comparison of Measures of Return to Work Following Treatment of Coronary Heart Disease

Purpose Methods of measuring return to work (RTW) following temporary disability are diverse. The purpose of this study was to compare different measures of RTW within a 12-month period using a well-defined population of patients treated with Percutaneous Coronary Intervention (PCI) and weekly administrative data on transfer payments. Methods Different RTW measures were defined based on weekly data from 12 months follow-up after PCI and agreement between definitions was expressed as Cohen's kappa. Prognostic factors for RTW were compared using logistic regression. Results Among those working before the PCI, 70 % were back to work at 6 months after the PCI and 76 % 1 year after when using cross-sectional measures and excluding those who left the workforce permanently during follow up. When using a time to event measure, 77 % experienced RTW during follow up, while only 60 % experienced RTW without recurrent sick-leave events during the following year. We found moderate to near perfect agreement when comparing the measures, with lowest agreement between the time-to-event measure without relapses compared to the other measures. When comparing prognostic factors for the different RTW outcomes, we found most associations similar in size, except from the clinical measure left ventricular ejection fraction, possibly related to recurrent sick leave. Conclusions Different measures revealed some differences in proportions of RTW. However, high agreement between RTW-definitions was found. Choice of RTW-definitions should depend on study purpose; simple cross-sectional methods are sufficient in prediction of RTW and analysis of risk factors, while methods capturing relapses are recommended when sustainability, prognosis and vulnerability are in focus.