Hurdle model of effect of available factors on the probability of work absenteeism (OR) and related cumulative PC costs (IRR) when compared with no treatment during the first 3 months after rheumatoid arthritis diagnosis.
| Characteristics | Logit Portion1, OR (95% CI) | p | Poisson Portion2, IRR (95% CI) | p |
|---|---|---|---|---|
| Female | 0.98 (0.89–1.09) | 0.77 | 0.64 (0.58–0.70) | < 0.001 |
| Age, yrs | 1.02 (1.01–1.03) | < 0.001 | 1.05 (1.04–1.06) | < 0.001 |
| RF present | 0.85 (0.78–0.94) | < 0.001 | 0.97 (0.89–1.05) | 0.45 |
| Medication, first 3 mos | ||||
| None | 1 (reference) | 1 (reference) | ||
| Single other | 0.79 (0.65–0.96) | 0.017 | 0.83 (0.70–0.97) | 0.017 |
| Single MTX | 0.65 (0.52–0.81) | < 0.001 | 0.76 (0.63–0.92) | 0.005 |
| Combination other | 0.80 (0.64–1.00) | 0.054 | 1.07 (0.89–1.28) | 0.49 |
| Combination including MTX | 0.86 (0.71–1.04) | 0.12 | 0.79 (0.68–0.93) | 0.004 |
↵1 Logit portion: considers the factor’s relationship with the incidence of productivity costs (i.e., PC > €0), showing with OR.
↵2 Negative binomial regression (zero-truncated) portion: considers the factor’s relationship with productivity costs (when the PC > €0), showing with IRR. PC: productivity costs; IRR: incidence rate ratios; RF: rheumatoid factor; MTX: methotrexate.