TABLE 3—
Final Cox Proportional Hazards Regression Model for Time to First Dental Examination for Medicaid-Enrolled Children (n = 6322) in Iowa: 2000–2008
| Model Covariate | Hazard Ratio (95% CI) | P |
| Main predictor variables | ||
| WBV frequency | ||
| Period 1 | 0.97 (0.93, 1.02) | .203 |
| Period 2 | 2.96 (1.41, 6.15) | .004 |
| Time-dependent covariate: Period 2 * [log(time) − mean log(time)] | 0.76 (0.63, 0.93) | .006 |
| Period 3 | 1.25 (1.14, 1.36) | <.001 |
| Age at first well baby visit | ||
| Rate of the first WBV | 6.07 (0.79, 46.65) | .083 |
| Interaction between the rate of the first WBV and the time at which the first WBV took place | 1.00 (0.99, 1.01) | .64 |
| Ascribed factors | ||
| Sex | .243 | |
| Female | 0.95 (0.86, 1.04) | |
| Male (Ref) | 1.00 | |
| Race | ||
| White (Ref) | 1.00 | |
| Non-White | 1.14 (1.02, 1.28) | .02 |
| Unknown or missing | 1.16 (0.89, 1.53) | .276 |
| At risk for developing a chronic condition | .443 | |
| No (Ref) | 1.00 | |
| Yes | 0.96 (0.87, 1.07) | |
| Eligibility for Medicaid through the Supplemental Security Income Program | .281 | |
| No (Ref) | 1.00 | |
| Yes | 0.82 (0.57, 1.18) | |
| Proximal factors | ||
| Saw different medical providers for WBVs | .001 | |
| No (Ref) | 1.00 | |
| Yes | 0.10 (0.02, 0.41) | |
| Time-dependent covariate: Saw different medical providers for WBVs * [log(time) − mean log(time)] | 0.56 (0.38, 0.83) | .004 |
| Immediate factor | ||
| Mother used any preventive dental care in the 12 mo before the child was born | <.001 | |
| No (Ref) | 1.00 | |
| Yes | 1.40 (1.25, 1.57) | |
| Intermediate factor | ||
| Rurality | ||
| Metropolitan (Ref) | 1.00 | |
| Urban adjacent to metropolitan | 1.00 (0.89, 1.14) | .956 |
| Urban nonadjacent to metropolitan | 1.05 (0.93, 1.19) | .458 |
| Rural | 1.16 (0.96, 1.41) | .133 |
| Distal factor | ||
| Lived in a dental Health Professional Shortage Area | .207 | |
| No (Ref) | 1.00 | |
| Yes | 0.94 (0.85, 1.04) | |
Note. WBV = well baby visit.