Combining data on NHSC program participants from administrative sources with Provider360 and Medicare data, we examined the retention trends in HPSA locations of participants in comparison to non-participants serving in HPSAs. We found that about 49% of NHSC Primary Care (PC) participants were located in the same HPSA one year after obligation completion and 82% were located in any HPSA. Also, by the 6th year after obligation, 35% of participants were located in same the HPSA and 72% of them in any HPSA.
In comparison, non-participant primary care retention in HPSAs is higher, but the difference was much bigger for retention in same HPSA than retention in any HPSA locations. We found that 91 % of the non-participants working in primary care HPSAs remain in the same county same HPSA in the first year after they are first observed in a HPSA. The retention rate declines constantly over the years, such that the retention rate reaches 69% in the 6th year since start year. The rates are higher in the case of ‘any HPSA’, ranging from 95% in the first year since start year to 82% in the 6th year since start year.
These findings indicate that much of the geographic mobility of participants that occurs after program completion is from one HPSA to another. Moreover, the convergence of retention rates over the longer run implies that after an initially higher mobility, NHSC participants have better retention in HPSAs than non-participants. Also, participants are only slightly more likely than non-participants to relocate within a county to a non-HPSA zip code or to relocate to a non-HPSA county. The findings are of similar magnitude for providers serving in mental health HPSAs.
Next, controlling for demographic characteristics, cohort, calendar year, and local area economic characteristics in a multivariate regression framework reduces the mean retention differences discussed above. The regression-adjusted difference between participants and non-participants’ probability to remain in the same HPSA same county location is -37% in the first year since separation/start and it is -21% in the 6th year since separation/start year in the case of primary care providers. The similarly calculated difference for the ‘any HPSA’ outcome shows a -11% difference in the first year and a -8% difference in the 6th year since separation/start year.
In addition, the regression analysis revealed that retention rises significantly with age, but differences by gender, provider type and Census division are small. Also retention is significantly related to zip code-level economic characteristics such as the poverty rate and other local area characteristics (at the zip code level), like percent White, percent Black or percent individuals with a high school degree that are ages 25 or above. These effects suggest that providers select into underserved areas based on the strength of their preferences for serving underserved populations.
Finally, our findings are consistent with an economic model predicting higher non-participant retention in HPSAs due to their self-selection into HPSAs without the financial inducement of NHSC programs. As we show in Chapters VI and VIII, the model predicts that NHSC programs increase total provider-years in HPSAs when the HPSA retention among participants is lower than that of non-participants.