International trends and social disparities in pain of adults aged 50 years and older in 22 countries across Europe, Asia, and the Americas: a longitudinal population-based study

Background: The experience of pain is highly prevalent among older adults worldwide. This study aimed to compare trends and social disparities in pain for middle aged and older adults (ie, those aged ≥50 years) across countries to help identify high-pain or high-disparity hotspots needing intervention, and low-pain or low-disparity locations or timepoints from which policy and practice lessons could be drawn. Methods: Country-specific pain trends were estimated using longitudinal logistic regressions on harmonised data for 212 904 adults aged older than 50 years observed repeatedly from 1998 to 2018 in 22 countries across three continents. Findings: Unadjusted pain prevalence was 43·21% (95% CI 43·10–43·33) across all countries and years pooled. Instrument-adjusted prevalence ranged from 26·70% (95% CI 25·52–27·88; Netherlands, 2006) to 59·20% (58·02–60·38; France, 2016). Over the decade 2006–16, when most countries were observed, prevalence substantially increased in 15 countries (12·01 percentage points), decreased in China (6·60 percentage points), and remained steady in six countries. Prevalence was higher among women, those with less education (ie, completed less than high school), and older respondents (those aged >60 years), though disparities varied substantially across countries. Disparities widened over time in some countries (eg, Spain), but remained stable, declined, or reversed in others (eg, Sweden). In 2016, Denmark had the lowest overall pain disparity index, while South Korea had the highest. Interpretation: There was a substantial increase in pain prevalence among middle aged and older adults in most countries studied. Cross-country, temporal, and sociodemographic variation indicates pain should be treated as a population public health issue. Funding: Agencia Nacional de Investigación y Desarrollo, National Institute on Aging.