TY - JOUR T1 - Predicting the duration of sickness absence spells due to back pain: a population-based study from Sweden JF - Occupational and Environmental Medicine JO - Occup Environ Med SP - 115 LP - 121 DO - 10.1136/oemed-2019-106129 VL - 77 IS - 2 AU - Annina Ropponen AU - Katalin Gémes AU - Paolo Frumento AU - Gino Almondo AU - Matteo Bottai AU - Emilie Friberg AU - Kristina Alexanderson Y1 - 2020/02/01 UR - http://oem.bmj.com/content/77/2/115.abstract N2 - Objectives We aimed to develop and validate a prediction model for the duration of sickness absence (SA) spells due to back pain (International Statistical Classification of Diseases and Related Health Problems 10th Revision: M54), using Swedish nationwide register microdata.Methods Information on all new SA spells >14 days from 1 January 2010 to 30 June 2012 and on possible predictors were obtained. The duration of SA was predicted by using piecewise constant hazard models. Nine predictors were selected for the final model based on a priori decision and log-likelihood loss. The final model was estimated in a random sample of 70% of the SA spells and later validated in the remaining 30%.Results Overall, 64 048 SA spells due to back pain were identified during the 2.5 years; 74% lasted ≤90 days, and 9% >365 days. The predictors included in the final model were age, sex, geographical region, employment status, multimorbidity, SA extent at the start of the spell, initiation of SA spell in primary healthcare and number of SA days and specialised outpatient healthcare visits from the preceding year. The overall c-statistic (0.547, 95% CI 0.542 to 0.552) suggested a low discriminatory capacity at the individual level. The c-statistic was 0.643 (95% CI 0.634 to 0.652) to predict >90 days spells, 0.686 (95% CI 0.676 to 0.697) to predict >180 spells and 0.753 (95% CI 0.740 to 0.766) to predict >365 days spells.Conclusions The model discriminates SA spells >365 days from shorter SA spells with good discriminatory accuracy. ER -