The estimation of DID regression models is based on the number of eligible providers; the volume of claims for PCIP eligible E&M services and the allowed charges/payments associated with those claims. The volume of E&M claims and payments analyzed here excludes those for hospital inpatient, ER, drug and laboratory services. As we explain above, Medicare providers with a PCIP-eligible specialty (i.e., family practice, internal medicine, geriatrics, pediatrics, NP, PA and clinical nurse specialists) that have at least one Medicare claim are included in the “treatment” group. These are the providers who are likely to be affected by the Medicare PCIP policy. Given that the announcement of the PCIP program was made in 2010,40 we assumed that the providers with Medicare PCIP eligible specialties would be potentially responsive to the incentive as early as year 2010. Therefore, years 2010 and 2011 represent the post-policy period.
The DID regression models were estimated using several sub-samples: (1) all providers; (2) only providers that appear in all 7 years of data (roughly 44 percent of all providers); (3) providers who were near the PCIP eligibility criteria in 2009 (i.e., restricted to providers who had the share of total Medicare claim payments -- allowed charges-- between 50 percent and 65 percent for PCIP eligible E&M services. About 15 percent of all providers in the sample met this restriction.
In Exhibit 11 we summarize the average volume of PCIP eligible E&M claims and the allowed charges/payments associated with those claims by select patient category and CPT code for providers in the “treatment” group. Comparing the first and last columns, we observe that providers near the 60 percent eligibility threshold generate more E&M claims, on average, compared to the average PCP accepting Medicare (895 vs. 590).
Exhibit 11: Number of PCIP Eligible E&M Claims and Mean Allowed Charges per Provider per Year by Types of Claims for Providers with PCIP Eligible Specialty, 2005-2011
Note: Summary of PCIP eligibility criteria. Primary care physicians (with internal medicine, family practice, pediatrics and geriatrics specialty) who have at least 60 percent of the practitioner’s allowed charges under the Medicare physician fee schedule (excluding hospital inpatient care and emergency department visits) are eligible for primary care services. The PCIP eligible primary care services are defined by specific E&M codes. Medicare PCIP is also provided to physician assistants, nurse practitioners and clinical nurse specialists who meet the similar eligibility criteria. For the purpose of our analysis we consider the PCPs (with the PCIP eligible specialty) who have 50 percent-65 percent of their services for PCIP eligible E&M services (defined by specific E&M codes) in 2009 are considered to be near the eligibility threshold.
For the control group, the number of providers, the volume of their Medicare claims for E&M services and the associated allowed charges for the providers with the PCIP non-eligible specialties are presented in Exhibit 12. As expected, providers in the control group generated much fewer E&M claims compared to providers in the treatment group. Specifically, providers in the control group supplied less than half the volume of E&M services compared to providers in the treatment group (i.e., 296 vs. 590).
Exhibit 12: Number of PCIP Eligible E&M Claims and Mean Allowed Charges per Provider per Year by Types of Claims for Providers with PCIP Non-Eligible Specialty, 2005-2011
40 Source: Patient Protection and Affordable Care Act (‘‘PPACA’’; Public Law 111–148). For our analysis we report a single estimate of PCIP impact under each regression model where year 2010 and 2011 are considered as the post-policy periods. We performed several sensitivity analyses to investigate if the estimated impact is significantly different between 2010 and 2011; we also checked if the results change once we consider 2011 as the only post period. Based on such detailed analysis we did not find any systematic evidence that the estimated impact is different between these two years and they are not sensitive to the choice of post-policy period.