Abstract
A method for combining matched and unmatched data is described and was applied to the results of randomized, controlled trials of photocoagulation in the treatment of diabetic retinopathy. A pooled estimate from the matched and unmatched studies war obtained by adaptation of the Mantel-Haenszel method, where the strata were unmatched studies and matched pairs within studies. A test of significance was based on the Mantel-Haenszel chi-square statistic, the latter also being used to calculate test-based confidence intervals. A test of homogeneity was performed by combining Mantel-Haenszel chi-square statistics from the matched and unmatched studies. By these methods, the combined estimate of the risk of deterioration of visual acuity for those receiving photocoagulation (relative to a risk of unity for those not receiving photocoagulation) was 0.37 (95 per cent confidence interval 0.29-0.46). The chi-square statistic (1 df) for an effect of treatment was 87.75 (p < 0.0001). The chi-square statistic for homogeneity of relative risk among studies was 11.20 (4 df, p < 0.05). However, this result was influenced disproportionately by one small matched study.
Original language | English (US) |
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Pages (from-to) | 371-378 |
Number of pages | 8 |
Journal | American Journal of Epidemiology |
Volume | 130 |
Issue number | 2 |
DOIs | |
State | Published - Aug 1989 |
Externally published | Yes |
Keywords
- Epidemiologic methods;
- Statistics
ASJC Scopus subject areas
- Epidemiology