Prevalence of musculoskeletal pain in the general Swedish population from 1968 to 2002: age, period, and cohort patterns.

We examined age, period, and cohort patterns in musculoskeletal pain prevalence between 1968 and 2002 in the Swedish population. A repeated nationally representative survey allowed cross-sectional comparisons of ages 18-75 (5 waves n≈5000), and ages 77+ at later waves (2 waves n≈500). Cross-sectional 10-year age group differences in 5 waves, time-lag differences between waves (shifts across time) for age groups, and within-cohort differences between waves for 10-year birth cohorts followed over time were analyzed using graphs and ordered logistic regressions. The outcome scale was based on the three items measuring slight or severe pain in back, shoulder, and joints during the past 12 months. Age-period-cohort models showed that pain prevalence increased with age - mild or severe at all locations. Adjusted for the age-related increase, the cohorts followed over time did not show significant period change, except for cohorts born during 1940s. Beginning with the 1940s' cohorts pain prevalence increased over the period, and after baseline later cohorts also entered adulthood and the study with a higher pain prevalence. The prevalence of pain in the adult population thus increased with the passage through age and time of the 1940s cohorts. While there were no pronounced cohort differences at baseline in 1968, results demonstrated strong age effects in pain. The results indicate that the prevalence of musculoskeletal pain among the oldest age groups may increase in the future, when more baby-boomers are entering their oldest ages.