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Table 3 Results of subgroup analyses by outcome type and NSAIDs type

From: Effect of aspirin and other non-steroidal anti-inflammatory drugs on prostate cancer incidence and mortality: a systematic review and meta-analysis

Study characteristics Number of studies OR (95% CI) P OR value Effect model Heterogeneity
      I 2 (%) Pvalue
Risk of prostate cancer incidence       
Any NSAIDs       
Studies of total prostate cancer 11 0.90 (0.75, 1.07) 0.25 Random 93.5 <0.001
Case–control studies 8 0.97 (0.79, 1.20) 0.78 Random 93.8 <0.001
Cohort studies 3 0.71 (0.47, 1.07) 0.10 Random 81.4 0.005
Studies in North America 6 0.73 (0.60, 0.88) 0.001 Random 79.6 <0.001
Studies in Europe 5 1.29 (1.25, 1.34) <0.001 Fixed 37.2 0.17
Studies of advanced prostate cancer 5 0.86 (0.52, 1.40) 0.54 Random 94.2 <0.001
Aspirin       
Studies of total prostate cancer 23 0.92 (0.87, 0.97) 0.002 Random 66.2 <0.001
Case–control studies 13 0.92 (0.85, 0.99) 0.040 Random 63.7 0.001
Cohort studies 10 0.91 (0.83, 0.99) 0.040 Random 71.7 <0.001
Studies from North America 16 0.92 (0.86, 0.97) 0.003 Random 53.7 0.006
Studies from Europe 7 0.94 (0.82, 1.08) 0.40 Random 80.7 <0.001
High quality studies 8 0.89 (0.81, 0.98) 0.022 Random 77.2 <0.001
Long-term aspirin use (≥4 years) 8 0.88 (0.79, 0.99) 0.038 Random 66.8 0.004
Studies of advanced prostate cancer 13 0.81 (0.73, 0.89) <0.001 Fixed 23.9 0.20
Case–control studies 7 0.84 (0.73, 0.98) 0.025 Fixed 23.7 0.18
Cohort studies 6 0.77 (0.67, 0.89) <0.001 Fixed 23.5 0.26
Studies from North America 9 0.82 (0.75, 0.89) <0.001 Fixed 14.0 0.32
Studies from Europe 4 0.88 (0.75, 1.03) 1.22 Fixed 48.2 0.12
High quality studies 6 0.81 (0.72, 0.92) 0.002 Fixed 38.1 0.152
Studies of non-advanced prostate cancer 6 0.96 (0.87, 1.07) 0.460 Fixed 33.6 0.177
Non-aspirin NSAIDs       
Studies of total prostate cancer 17 1.01 (0.90, 1.13) 0.86 Random 90.1 <0.001
Case–control studies 11 0.97 (0.81, 1.17) 0.74 Random 93.0 <0.001
Cohort studies 6 1.07 (0.95, 1.20) 0.25 Random 69.6 0.006
Studies from North America 11 0.94 (0.85, 1.05) 0.28 Random 68.8 <0.001
Studies from Europe 6 1.18 (1.06, 1.32) 0.002 Random 71.1 0.004
Studies of advanced prostate cancer 9 0.99 (0.77, 1.28) 0.97 Random 81.6 <0.001
Studies of non-advanced prostate cancer 3 1.00 (0.90, 1.12) 0.943 Fixed 0.0 0.897
Any COX2 inhibitors       
Studies of total prostate cancer 5 1.10 (0.90, 1.33) 0.36 Random 48.7 0.099
Studies of advanced prostate cancer 3 1.20 (0.79, 1.83) 0.40 Fixed 0.0 0.87
Risk of prostate cancer-specific mortality       
Any NSAIDs (including aspirin use alone)       
Studies of total prostate cancer 8 1.00 (0.68, 1.47) 0.99 Random 95.3 <0.001
Aspirin       
Studies of total prostate cancer 6 0.86 (0.78, 0.96) 0.005 Fixed 39.2 0.15
Studies from North America 3 0.85 (0.50, 144) 0.55 Random 63.8 0.063
Studies from Europe 3 0.85 (0.76, 0.95) 0.005 Fixed 12.8 0.32
  1. CI, confidence interval; COX-2, cyclooxygenase enzymes-2; OR, odds ratio.