Parkinson disease male-to-female ratios increase with age: French nationwide study and meta-analysis.
Level 1 - systematic review of randomized trials
Meta-analysis of observational incidence studies combined with a nationwide population-based cohort.
PubMed 26701996 · doi:10.1136/jnnp-2015-312283
What was done
Researchers examined whether male-to-female (M-F) ratios in Parkinson's disease (PD) vary with age. They analyzed 2010 French national drug claims databases to identify PD cases with a validated algorithm, using Poisson regression to calculate age-specific M-F prevalence and incidence ratios and their change per 10 years of age. They also conducted a meta-analysis of 22 PD incidence studies containing age- and sex-specific data.
What was found
In the French dataset (149,672 prevalent cases, 50% women; 25,438 incident cases, 49% women), age-standardized rates were higher in men than women for both prevalence (2.865 vs. 1.934 per 1,000) and incidence (0.490 vs. 0.328 per 1,000 person-years), yielding overall M-F ratios of 1.48 and 1.49, respectively. M-F ratios increased per 10 years of age by 0.05 for prevalence and 0.14 for incidence. Incidence was comparable between sexes under age 50 (M-F ratio <1.2, p > 0.20), but diverged to >1.6 in individuals older than 80 years (p < 0.001; p-trend < 0.001). The meta-analysis of 22 studies (14,126 cases, 46% women) confirmed an increase in M-F incidence ratio of 0.26 per 10 years of age (p-trend = 0.005).
Why it matters
This study shows that male predominance in PD is age-dependent rather than uniform across the lifespan. This indicates that sex-specific hormonal, genetic, or environmental protective and risk factors likely exert differing influences across different age windows.
Limits
The nationwide French cohort relied on administrative drug claims algorithms rather than standardized clinical diagnostic examinations, creating potential for diagnostic misclassification. Confounding risk factors (e.g., occupational exposures, smoking, estrogen exposure) and subtype variations were not detailed in the abstract.
Cited by
- context Parkinson's disease occurs in approximately 1.8 men for every woman, while Alzheimer's disease affects roughly twice as many women as men.