Distribution of patients with rheumatoid arthritis (RA), person-years and registry-derived diagnoses of progressive multifocal leukoencephalopathy (PML) by exposure to biological agents and in general population comparators: crude and age- and sex-standardised incidence rates (IR) with 95% CIs
| Exposure group | No of subjects | No of person-years | No of cases of PML* | Age- and sex-standardised IR† per 100 000 person-years (95% CI)‡,§ |
|---|---|---|---|---|
| General population | 286949 | 1858645 | 5 | 0.3 (0.1 to 0.6) |
| RA, overall | 66278 | 402443 | 4 | 1.0 (0.3 to 2.5) |
| Biological-naive | 65548 | 362032 | 3 | 0.8 (0.2 to 2.5) |
| Biological-exposed | 8426 | 40200 | 1 | 2.3 (0.1 to 71) |
*Registry-derived diagnoses of PML.
†Rates standardised using age and sex distribution in the overall RA population.
‡Crude IRs were similar to age- and sex-standardised IRs.
§Approximation of exact CI based on the gamma distribution.