Table 2

Relationship between multimorbidity and absolute† and share‡ of total costs generated through inpatient, outpatient and pharmacy care among high-cost VA patients

Number of body systems affected by chronic conditionsnTotal§InpatientOutpatientPharmacy
Predicted costsPredicted costsPredicted share of totalPredicted costsPredicted share of totalPredicted costsPredicted share of total
130 77270 67141 53150.716 19628.044687.5
254 83769 34240 18351.317 88330.342807.2
366 61071 01040 40350.519 39532.043927.4
453 93773 45541 48149.720 87933.646137.6
530 50975 45542 46649.122 03434.850017.9
612 56678 80744 08948.323 44835.853408.3
7+441981 54444 99447.424 93836.959528.7
Average difference¶1774*577*−0.6*1444*1.6*199*0.2*
  • *p<0.01.

  • †Predicted absolute costs are generated via multivariate linear regression examining associations between number of body systems affected by chronic conditions and costs, adjusting for age, sex, race/ethnicity, marital status, homelessness and insurance status.

  • ‡Predicted shares of total cost are generated via fractional logit regression examining associations between the number of body systems affected by chronic conditions and shares of total cost within each domain of care, adjusting for age, sex, race/ethnicity, marital status, homelessness and insurance status.

  • §Component costs and cost shares sum approximately to total when VA-sponsored contract care (omitted for clarity) is included. Note that dividing predicted component costs by predicted total costs does not equal the predicted share of total. The former is a ratio of means and the latter is a mean of ratios, and although both procedures estimate the same quantity, they are not guaranteed to produce the same result. The two procedures do, however, produce comparable results.

  • ¶Average differences represent change in costs (for absolute costs) or percentage point change in share of cost (for share of total cost generated within each domain of cost) for each additional body system affected by chronic conditions.