Treatment adherence among patients with bipolar or manic disorder taking atypical and typical antipsychotics.
OBJECTIVE
This retrospective claims-based study evaluated treatment adherence among patients with bipolar or manic disorder treated with atypical and typical antipsychotics.


METHODS
Claims data for 18,158 antipsychotic treatment episodes in 15,224 commercially insured patients with bipolar or manic disorder (ICD-9-CM criteria), from January 1999 through August 2003, were evaluated. Overall adherence was measured by adherence intensity (medication possession ratio) and treatment duration (length of treatment episodes). Treatment-related factors that may affect medication adherence were also investigated. Pairwise comparisons of the individual atypicals and a combined group of leading typical antipsychotics were undertaken using multiple regression analysis adjusting for differing patient characteristics.


RESULTS
Adherence intensity with quetiapine was 3% greater than with the typicals combined (p=.002) and was greater than with risperidone or olanzapine by 4% (p<.001) and 2% (p=.001), respectively. Olanzapine (2%, p<.001) and ziprasidone (3%, p=.001) showed significantly greater adherence intensity than risperidone. Risperidone (p=.002), olanzapine (p=.055), and the typicals (p=.021) demonstrated negative associations between dose and adherence intensity, while quetiapine showed a nonsignificant trend for a positive association (p=.074). Quetiapine and risperidone had significantly longer treatment durations than the typicals combined (1.05 and 1.00 months, respectively, p<.001) and longer treatment durations than olanzapine (0.75 and 0.79 months, respectively, p<.001) or ziprasidone (0.78 months, p=.002 and 0.69 months, p=.003, respectively). Shorter treatment durations were associated with switching to other antipsychotics or remaining on or switching to other psychotropics (e.g., traditional mood stabilizers) only. All of the atypicals except ziprasidone were associated with a significantly lower likelihood of switching compared with the typicals (p<.05).


CONCLUSIONS
The claims-based findings of this study suggest that, for bipolar or manic disorder, quetiapine therapy may be associated with better treatment adherence than typical or some atypical antipsychotics. Estimated differences, however, were relatively small, particularly for adherence intensity.
Gianfrancesco
Frank D
FD
HECON Associates, Inc., Montgomery Village, MD 20886, USA. heconassoc@comcast.net
Rajagopalan
Krithika
K
Sajatovic
Martha
M
Wang
Ruey-hua
RH
D000328:Adult; D014150:Antipsychotic Agents / Q000191:economics / Q000627:therapeutic use*; D001569:Benzodiazepines / Q000627:therapeutic use; D001714:Bipolar Disorder / Q000175:diagnosis / Q000188:drug therapy*; D003987:Dibenzothiazepines / Q000627:therapeutic use; D016527:Drug Costs; D011307:Drug Prescriptions / Q000706:statistics & numerical data; D017723:Drug Utilization Review / Q000379:methods; D017050:Episode of Care; D005500:Follow-Up Studies; D006801:Humans; D007345:Insurance Claim Review / Q000706:statistics & numerical data; D038801:International Classification of Diseases; D008875:Middle Aged; D000077152:Olanzapine; D010349:Patient Compliance; D010879:Piperazines / Q000627:therapeutic use; D000069348:Quetiapine Fumarate; D012044:Regression Analysis; D012189:Retrospective Studies; D018967:Risperidone / Q000627:therapeutic use; D013844:Thiazoles / Q000627:therapeutic use; D016896:Treatment Outcome
D014150:Antipsychotic Agents; D003987:Dibenzothiazepines; D010879:Piperazines; D013844:Thiazoles; D001569:Benzodiazepines; D000069348:Quetiapine Fumarate; C092292:ziprasidone; D018967:Risperidone; D000077152:Olanzapine