Table 3

Pooled risk estimates for Parkinson’s disease by exposure assessment method, study design, publication year period and geographic region, based on meta-analysis of articles on occupational pesticide exposure published between 1990 and 2020.

Number of risk estimatessRR95% CIHeterogeneity measures
I2 (%)P valueQP value
Exposure assessment method1.200.55
Group-level61.341.16 to 1.5400.54
Self-reported exposure221.451.18 to 1.7656<0.01
Expert level91.561.21 to 2.01180.28
Study design2.820.24
Cohort (prospective)81.280.95 to 1.7363<0.01
Cohort (retrospective)11.140.77 to 1.68..
Case–control281.541.34 to 1.77270.09
Publication year period1.490.22
1990–2006191.581.32 to 1.89360.06
2007–2020181.341.12 to 1.62480.01
Geographic region1.920.38
Europe141.471.21 to 1.79370.08
USA191.531.24 to 1.8851<0.01
Other41.170.85 to 1.62300.23
Case–control studies only
Exposure assessment method0.600.74
Group-level31.481.02 to 2.1500.39
Self-reported exposure201.511.24 to 1.83420.02
Expert level51.701.31 to 2.200.88
Exposure assessment method during publication year periods
Exposure assessment method1.240.54
Group-level31.571.09 to 2.27370.20
Self-reported exposure131.521.2 to 1.93370.09
Expert level32.381.12 to 5.03280.25
Exposure assessment method0.620.73
Group-level31.230.93 to 1.6200.83
Self-reported exposure91.340.95 to 1.8870>0.01
Expert level61.421.12 to 1.8100.49
  • I2=percentage of variation across studies due to heterogeneity. Q=Cochran’s Q.

  • sRR, summary risk ratio.