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The effects of level of transformation in primary care on healthcare utilization and cost among a Medicare cohort
The Patient-Centered Medical Home (PCMH) is an emerging strategy to attain the triple aims of improved quality of care, improved health of populations, and reduced health care costs. There has been a paucity of longitudinal analyses at the patient level of the effects of individual components of the PCMH. Furthermore, implementation of the PCMH is complex and consists of several elements including planned care and care team interventions that have received insufficient individual attention. The objectives of this paper were to: 1) examine the relationship between level of transformation to a PCMH over time and cost, and identify the impact on cost of the individual core element(s) of the PCMH.
Study Population
The study sample included a cohort of elderly patients with specific chronic conditions exposed to a variant of the PCMH, called Care by Design (CBD), in a network of clinics associated with an academic medical center. Inclusion criteria were: (1) 12 months of continuous health plan enrollment during each year, (2) living on at the end of each year, and (3) receiving > 50% of their primary care at one of the University of Utah primary care clinics during each year. The sample consisted of the 10697 Medicare enrollees in 2007. The analytic sample was a subset of 3802 enrollees with diagnoses of coronary artery disease (CAD), diabetes mellitus (DM), or heart failure (HF).
Data
Comprehensive Medicare records on cost and utilization from 2007 through 2009.
Implementation Measures
An internally developed tool was used to measure the level of CBD implementation on three principles: appropriate access (AA), planned care (PC) and Care Team (CT). Implementation scores ranged from 0 to 4, with higher values indicating higher implementation.
Analytical Methods
Generalized estimation equations (GEE) with unstructured correlations and gamma distributions along with log link functions were used. GEE models, controlling for patient-level demographic characteristics (age, gender, and health status), and number of clinic visits each year and number of co-morbid conditions were run to estimate total costs (sum of outpatient, inpatient, and pharmaceutical costs) in a two-year followup. All costs were adjusted to 2009 dollars using Medicare price indices.
Results
Patients with CAD, DM and HF diagnoses were 27.7%, 26.9%, and 16.8%, respectively. Average (SD) of age was 77.1 (7.6) years old and proportion of females was 59.7%. Median total cost was $3529 (25% and 75% quartiles: $1392 and $9807) in 2007. After controlling for covariates, regardless of level of implementation, clinics did not see increases in cost over time. Levels of implementation of CT (p=0.348) and AA (p=0.652) do not appear to impact cost over time. No increase in cost could be explained by differences in healthcare services utilization. Following transformation, outpatient services may increase, while inpatient services may decrease. Our analyses will explore such changes.
Conclusions
Transformation is complex and our analytic window may have been too short to demonstrate cost impacts. It is necessary to evaluate the effect of PCMH over the long-term. Outcomes are sensitive to the measurement of implementation. Well defined and validated measurement tools are critical.