Modifiable factors explaining improved hearing in Swedish 70-year-olds over four decades: a mediation analysis

Objective: To explain improved hearing in more recently born cohorts of 70-year-olds in Sweden by examining mediating roles of educational level, occupational group, systolic blood pressure, and smoking. Design: A repeated cross-sectional analysis using two age-homogeneous birth cohorts from the Gothenburg H70 Birth Cohort Studies. To investigate mechanisms underlying cohort differences in hearing, mediation analyses were used to assess direct and indirect effects of cohort via educational level, occupational group, smoking, and systolic blood pressure. Study sample: Two samples of 70-year-olds were included (mean age 70.5 years), four decades apart (1901-1907, n = 674; 1944, n = 1114). Participants underwent standardized health examinations, including audiometric testing. Results: Educational level was the primary mediator, accounting for 1.19 dB of the 6.16 dB difference in PTA4 between cohorts, followed by occupational group (0.74 dB) and smoking habits (0.28 dB). In sex-stratified analyses, educational level was the dominant mediator among women (1.63 dB of 4.8 dB), whereas occupational group played a larger mediating role among men (0.75 dB of 7.7 dB). Conclusions: This study found that changes in lifestyle and socioeconomic factors, specifically education, occupation, and smoking, explain some of the trend of better hearing in recent generations of 70-year-olds, underscoring their relevance for preventive strategies.