Multimorbidity and healthcare utilisation among high-cost patients in the US Veterans Affairs Health Care System

Abstract

Objectives: To investigate the relationship between multimorbidity and healthcare utilisation patterns among the highest cost patients in a large, integrated healthcare system.

Design: In this retrospective cross-sectional study of all patients in the U.S. Veterans Affairs (VA) Health Care System, we aggregated costs of individuals' outpatient and inpatient care, pharmacy services and VA-sponsored contract care received in 2010. We assessed chronic condition prevalence, multimorbidity as measured by comorbidity count, and multisystem multimorbidity (number of body systems affected by chronic conditions) among the 5% highest cost patients. Using multivariate regression, we examined the association between multimorbidity and healthcare utilisation and costs, adjusting for age, sex, race/ethnicity, marital status, homelessness and health insurance status.

Setting: USA VA Health Care System.

Participants: 5.2 million VA patients.

Measures: Annual total costs; absolute and share of costs generated through outpatient, inpatient, pharmacy and VA-sponsored contract care; number of visits to primary, specialty and mental healthcare; number of emergency department visits and hospitalisations.

Results: The 5% highest cost patients (n=261,699) accounted for 47% of total VA costs. Approximately two-thirds of these patients had chronic conditions affecting ≥3 body systems. Patients with cancer and schizophrenia were less likely to have documented comorbid conditions than other high-cost patients. Multimorbidity was generally associated with greater outpatient and inpatient utilisation. However, increased multisystem multimorbidity was associated with a higher outpatient share of total costs (1.6 percentage points per affected body system, p<0.01) but a lower inpatient share of total costs (-0.6 percentage points per affected body system, p<0.01).

Conclusions: Multisystem multimorbidity is common among high-cost VA patients. While some patients might benefit from disease-specific programmes, for most patients with multimorbidity there is a need for interventions that coordinate and maximise efficiency of outpatient services across multiple conditions.

Keywords: GERIATRIC MEDICINE; HEALTH SERVICES ADMINISTRATION & MANAGEMENT; PRIMARY CARE.

Figure 1

Prevalence of body systems affected by chronic conditions and multisystem multimorbidity among high-cost VA patients (relative to remaining 95% of patients). Numbers at the top of each column represent the percentage of high-cost patients with one or more chronic conditions affecting the specified body system. Numbers within each cell represent the percentage of high-cost patients with chronic conditions affecting the dyad of body systems on both horizontal and vertical axes. Numbers in parentheses represent the relative prevalence when comparing high-cost patients with the remaining population. Shades highlight different prevalence levels, with darker shades representing higher rates (<5%, 5–9%, 10–19% and ≥20%, respectively). For the prevalence and relative prevalence of specific chronic conditions, see online supplementary appendix table 1. Circ, circulatory; Endo, endocrine; GI, gastrointestinal; GU, genitourinary; Inf, infectious; MH/D, Mental Health and Dementia; MS, musculoskeletal; Neo, neoplasm; NS, nervous system/sense organs; Resp, respiratory; SCI, spinal cord injury; VA, Veterans Affairs.

Figure 2

Variation in number of comorbidities among high-cost Veterans Affairs (VA) patients with common medical and mental health conditions (PTSD, post-traumatic stress disorder).