In the commercial group, patients on injected drugs were also significantly sicker, with an average Charlson comorbidity index of 0.58, compared with an average of 0.47 in the orally treated patients. Again, this pattern was reversed in Medicare patients, where the injected patients had an average Charlson comorbidity index score of 1.24, significantly less than the 1.83 average among patients on an oral drug.
The analysis also showed regional differences in the use of the two treatment options, with injections exceeding oral drug use in the North-Central U.S. region, while oral drugs were substantially more popular than injected drugs in the Western half of the United States. In other U.S. regions, the use of the two treatment routes was generally more balanced.
The study was sponsored by Otsuka, which markets the antipsychotic drug aripiprazole. Dr. Wong said he has been a consultant to Otsuka.