O4B.6 Do we need repeated measurements for reliable classification of case status regarding musculoskeletal pain?

Musculoskeletal disorders (MSDs) are major causes for disability, reduced work ability and early exit from the labour market. The aetiology is understood to be multifactorial and MSDs are known to have a recurrent course characterized by development, recovery, reoccurrence and chronic states. Studies classifying participants as suffering from e.g. low back pain based on self-reported symptoms solely at one time are therefore at risk of just capturing the point prevalence of pain and not a more representative state characterizing the participants.In order to investigate how well a classification based on self-reported musculoskeletal complaints of the neck, shoulders and lower back in a baseline questionnaire represents the situation of the respondents´ pain and functional status over a 12 month period, we analysed data collected in a study on 129 employees at selected Swedish home-care providers. The participants completed a baseline questionnaire on work environment and mental and physical health and responded to questions on the impact on work capacity of pain sent monthly to their phones by text messages.The results show that classification into cases and non-cases cases based on reported musculoskeletal complaints at baseline was a statistically significant predictor of persistent differences between groups with regard to pain and work capacity throughout the 12 months covered by text messages. The variation in work capacity over time seemed to be more pronounced in case groups.In conclusion, classifying respondents as cases and non-cases based on self-reported musculoskeletal complaints of the neck, shoulders and lower back at baseline seems to be a good predictor of persistent differences in self-reported work capacity due to neck, shoulder and low back pain during the following year.