Table 2. Factors predicting irritable bowel syndrome (IBS) incidence in Taiwan during 2003–2013 (N = 7 634 281).
| Variables | Crude IRR | 95% CI | P value a | Adjusted IRR | 95% CI | P valueb,c |
|---|---|---|---|---|---|---|
| Year | 0.98 | 0.98–0.99 | <.001 | 0.97 | 0.97–0.97 | <.001 |
| Age | 1.02 | 1.02–1.02 | <.001 | 1.03 | 1.02–1.03 | <.001 |
| Female sex | 1.12 | 1.10–1.14 | <.001 | 1.14 | 1.12–1.16 | <.001 |
| Insurance premium (NTD) | – | – | ||||
| >=40000 | 0.95 | 0.92–0.98 | <.001 | 1.15 | 1.12–1.19 | <.001 |
| 20000–39999 | 0.97 | 0.95–0.99 | 0.007 | 1.09 | 1.06–1.11 | <.001 |
| <20000 | 1.00 | 1.00 | ||||
| Urbanization c | ||||||
| Urban | 0.89 | 0.86–0.92 | <.001 | 1.05 | 1.01–1.09 | 0.017 |
| Suburban | 0.87 | 0.83–0.90 | <.001 | 1.00 | 0.96–1.04 | 0.808 |
| Rural | 1.00 | 1.00 |
IRR = incidence rate ration; CI = confidence interval.
a Tested by univariate Poisson regression with GEE model.
b Tested by multivariate Poisson regression GEE analysis.
c With missing data for the urbanization level variable (n = 749 662).