Assessing cost effects of nursing-home-based geriatric nurse practitioners

Health Care Financing Review, Spring, 1990 by Joan L. Buchanan, Robert M. Bell, Sharon B. Arnold, Christina Witsberger, Robert L. Kane, Judith Garrard

Continuing residents

Findings with respect to home-level variables were somewhat less consistent with our expectations for continuing residents than for new admissions, perhaps as a result of the lower sampling ratio for this group. Somewhat unexpectedly, continuing residents in skilled care facilities had lower expenditures in both models, and those in for-profit homes had marginally higher expenditures in one model. Findings with respect to bed size and hospital affiliation were similar to those for new admissions.

As anticipated, increased length of stay prior to the study observation period was a strong predictor of lower use. Longer study observation periods also predict lower use. The effect of age on average expenditures was similar to that found among new admissions, although not as significant: Older patients received fewer services and service use decreased with increasing age.

As expected, variables describing the patient at admission did not have as strong predictive power for continuing residents as for newly admitted patients. Patients admitted directly from the hospital had higher per diem expenditures, but the effect for admission to skilled care was marginal. Patients who were covered by Medicaid at admission had lower expenditures, as evidenced by consistently negative coefficients, although the coefficients were not statistically significant.

Medical services

For the new-admission sample, the GNP coefficients indicate that patients from GNP homes had higher per diem expenditures than patients from control homes in the pre-period. After adjusting the t-statistics to correct for the correlation across observations, this difference is significant at the 5-percent level in the continuing-resident models and at the 10-percent level in the new-admission models. Per diem expenditures for patients from control homes increased significantly during the post-period for new admissions.

Although not conclusive, our results for new admissions in GNP homes suggest that expenditures dropped in the post-period relative to the trend in control homes (GNP*POST coefficient). This relative decline was statistically significant at the 10-percent level. The retransformed net GNP effect was a change of -$2.65, or -15 percent. A 95-percent confidence interval for the change is from -28 percent to 1 percent. Other model variations, not shown here, included patient classification systems, Functionally Ranked Explanatory Designations, Katz score, the Minnesota Case-Mix System, resource utilization groups, number of ADL dependencies, and indicators for each ADL dependency. The relative decline attributed to GNPs was statistically significant at the 5-percent level in one of the eight model variations and at the 10-percent level in four more. In the remaining models, the size and sign of the coefficients were consistent with this finding, but the statistical precision needed to achieve significance is lacking. Using these classification systems, no differences in case mix were found between the treatment and control group.