Landmark T et al. – Compared with the longitudinal classification, a cross–sectional measure of moderate pain or more during the last week on the SF–8 scale presented a sensitivity of 82% and a specificity of 84%, and a sensitivity of 80% and a specificity of 90% when combined with a 6–month recall question. Thus pain reporting in the general population is stable and cross–sectional measures may give valid prevalence estimates of chronic pain.

• A random sample of 6419 participants from a population study (the HUNT 3 study in Norway) was invited to report pain on the SF-8 verbal pain rating scale every 3months over a 12-month period and to report pain lasting more than 6months at 12-month follow-up.
• Complete data were obtained from 3364 participants.

• Pain reporting was highly stable (intraclass correlation 0.66, 95% confidence interval 0.65 to 0.67), and the prevalence of chronic pain varied considerably according to level of severity and persistence: 31% reported mild pain or more, whereas 2% reported severe pain on 4 of 4 consecutive measurements.
• When defined as moderate pain or more on at least 3 of 4 consecutive measurements, the prevalence was 26%.