This study’s goal was to investigate content validity of the International Classification of Functioning, Disability and Health (ICF) Core Sets for low back pain (LBP), by examining whether common activities reported as difficult to perform are included in the Core Sets. Ninety-eight patients with long-lasting back pain (>3 months) between 18 and 65 years of age were consecutively recruited from a Multidisciplinary Outpatient Spine Clinic to participate in the cross-sectional study. Difficulties with daily life and work task activities because of back pain were examined by asking the patients two questions: 1) can you specify activities that are difficult to perform because of your back pain? and 2) are there specific work tasks that you are unable to do because of your back pain? Two raters independently classified the written responses according to the ICF Core Sets’ component Activities and Participation. Activities and work tasks were linked to 15 of 29 categories (52%) in the Comprehensive Core Set, and 9 of 12 (75%) in the Brief Core Set, and the initial agreement between the two raters in coding the answers according to the Core Sets was (83%, k = 0.80) and (93%, k = 0.9), respectively, before consensus was reached.
From this study it was concluded that the Comprehensive Core Set for LBP to a sizeable degree contains daily life and work-related activities often reported as difficult to perform by patients with long-lasting LBP. The categories, however, are very broad and fail to provide specified descriptions of the most frequently reported activity limitations such as sitting, standing and walking. The Brief Core Set does not include categories for frequently reported activities such as pulling/pushing and leisure/recreation activities. ICF Core Sets for LBP seem suitable for obtaining a gross overview of the patients’ functional limitations, but fail to provide adequate information from a therapeutic point of view.