Table 5. Incidence rate of possible DCS per 10,000 dives before and after the intervention stratified by size of the atrial defect; values in brackets are 95% confidence intervals except where indicated .
| Group (n) | PFO (n) | Before | After | Relative risk | P-value |
| Conservative (17) | Large (7) | 45 (16–99) | 445 (296–643) | 9.7 (4.0–23) | < 0.0001 |
| Small (10) | 30 (17–49) | 131 (72–221) | 4.4 (2.1–8.9) | < 0.05 | |
| Closure (34) | Large (26) | 219 (194–247) | 48 (31–70) | 0.2 (0.1–0.3) | < 0.0001 |
| Small (8) | 38 (25–55) | 31 (9–79) | 0.8 (0.3–2.3) | NS |