Table 2.
Assessment of certainty of evidence using the GRADE evidence profile
| Certainty assessment | No of patients | Effect | Certainty | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| No of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | endometriosis | control | Relative (95% CI) |
Absolute (95% CI) |
|
| Migraine | |||||||||||
| 13 | Observational studies | very seriousa | not serious | seriousb | not serious | strong association | 2,859/32,489 (8.8%) | 12,030/299,166 (4.0%) |
OR 2.25 (1.85 to 2.72) |
46 more per 1,000 (from 32 more to 62 more) |
⨁⨁◯◯ Lowa, b |
| Migraine without aura | |||||||||||
| 3 | Observational studies | very seriousc | not serious | seriousb | not serious | strong association | 137/482 (28.4%) |
63/488 (12.9%) |
OR 2.64 (1.89 to 3.69) |
152 more per 1,000 (from 90 more to 224 more) |
⨁◯◯◯ Very lowb, c |
| Migraine with aura | |||||||||||
| 3 | Observational studies | very seriousc | seriousd | seriousb | very seriouse | limited evidence, heterogeneity of findings |
28/482 (5.8%) |
8/488 (1.6%) |
OR 3.47 (0.53 to 22.89) |
37 more per 1,000 (from 7 fewer to 255 more) |
⨁◯◯◯ Very lowb, c,d, e |
CI: confidence interval; OR: odds ratio
Explanations
a. 50% of studies (n = 7) at very high risk of bias, 21% (n = 3) at high risk of bias, 14.5% of studies (n = 3) rated as ‘some concerns’, and 14.5% (n = 3) at low risk of bias
b. Multiple diagnostic methods accepted, various population settings (e.g. neurology clinic), not all studies excluded endometriosis in the control group (e.g. negative laparoscopy)
c. 67% (n = 2) rated as ‘some concerns’ and 33% (n = 1) at very high risk of bias
d. One study found similar rates in both groups
e. 95% CI 0.53–22.89