Bl. Svarstad et al., Using drug claims data to assess the relationship of medication adherence with hospitalization and costs, PSYCH SERV, 52(6), 2001, pp. 805-811
Objective: This naturalistic study used claims data to examine the relation
ship of medication nonadherence to hospital use and costs among severely me
ntally ill clients in Wisconsin. Methods: Data for 619 clients were obtaine
d from Medicaid drug and hospital claims, county records, and case managers
as part of a larger study in eight county-based mental health systems. Stu
dy participants were eligible for Medicaid, had a severe and persistent men
tal illness, were 18 years or older, and were receiving neuroleptics, lithi
um, or antidepressants. Drug claims were analyzed for a 12-month period to
determine how regularly clients obtained their medications. Regression anal
yses were used to assess the effects of irregular medication use on any hos
pitalization for psychiatric problems, the number of days hospitalized, and
hospital costs. The analyses controlled for several risk factors. Results:
Among clients with schizophrenia or schizoaffective disorder, 31 percent u
sed medications irregularly. The rates were 33 percent among those with bip
olar disorder and 41 percent among those with other severe mental illnesses
. In the total sample, irregular users had significantly higher rates of ho
spitalization than regular users (42 percent versus 20 percent), more hospi
tal days (16 days versus four days), and higher hospital costs ($3,992 vers
us $1,048). Irregular medication use was one of the strongest predictors Of
hospital use and costs even after the analyses controlled for diagnosis, d
emographic characteristics, baseline functioning, and previous hospitalizat
ions. Conclusions: The availability of drug claims data and the ability to
use them in predictive analyses make them a potentially useful data source
in studies of medication adherence among persons with severe mental illness
.