Information regarding diagnostic and treatment patterns among children with bipolar disorder were summarized in this aim. To achieve this, two study designs were used - a prevalence design (aim 1a) and an incident diagnosis design (aim 1b).
For Aim 1a, repeated cross-sections of data were used to identify the diagnostic prevalence of bipolar spectrum disorders and treatments for the disorders among a cohort of children under the age of 18 years. A retrospective cohort was constructed using MarketScan Commercial Claims and Encounters database from January 1, 2005 to December 31, 2007. Information regarding the demographic and treatment characteristics of children who were diagnosed with any bipolar spectrum disorder was assessed using frequency information for
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each variable of interest (e.g., age, gender, co-morbid conditions, treatment received). Cross- sections were extracted from January 1st to December 31st for each year (2005 - 2007).
The annual diagnostic prevalence of bipolar spectrum disorders used the total number of children with a specific bipolar diagnosis over each one-year study period (January 1 - December 31) divided by the total number of children in the dataset at the mid-point of the study period. Although this method did not allow us to account for the impact of non- continuous enrollment, it has been used previously in claims based annual-prevalence
studies.256 A patients' bipolar type (Bipolar I, II, Unspecified, or Cyclothymia) was classified according to the bipolar diagnosis code received at their last bipolar-related visit during the study year. In addition to the diagnostic prevalence, patient characteristics (e.g., age, gender, co-morbid conditions and disease severity), and physician specialty information were
summarized by study year for this sample.
Descriptive information regarding the medication classes and class combinations that were used to treat pediatric bipolar disorder were also summarized by year for the medication use sample. For this analysis, patients' bipolar type was classified according to the bipolar diagnosis code received at the last bipolar-related visit prior to December 1st in each calendar year. This was done to ensure that, for all included patients, their medication use could be observed for 30 days after their last diagnosis. Summaries included drug-level and class-level use, as well as a count variable that indicated the number of drugs taken by each child during the 30-days after their last diagnosis.
In addition to the summaries proposed above, changes in diagnosis, treatment and co- morbid conditions were also assessed by age categories for aim 1a. There is currently a lack
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of information regarding the differences in treatment strategies and diagnosis of children who are under the age of 10 years.22 This age group is particularly important because current recommendations are to conduct medication trials of only 10 to 17 year old children.20 Therefore, age categories were constructed to assess diagnosis, treatment and comorbidities for children under the age of 10 and those ages 10-17 separately. Each summary described above was replicated separately for those ages less than 10 years and those ages 10-17 years inclusive.
For Aim 1b, a sample of newly-diagnosed patients was constructed. This was achieved by requiring that patients have a 6 month "clean" period (no evidence of bipolar diagnosis or treatment) prior to their initial (first identified) diagnosis, followed by a 12 month period of continuous enrollment. Using this sample, patients were followed forward in time to determine if there were changes in their diagnoses or treatments (Figure 3.1). To be included in the aim 1b cohort, patients must have had their first diagnosis of bipolar disorder between July 1, 2005 and December 31, 2006. Patient characteristics were captured within the 6 month pre-diagnosis period and medication use was summarized within the 12 month follow-up period for each patient.
5Figure 3.1 Timeline for Assessments
Minimum 6 Month Pre-Diagnosis
First Diagnosis between July 1, 2005 and December 31, 2006
Minimum 12 Month Follow Up Period
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Patient characteristics (age at diagnosis, gender, geographic region, insurance type, generosity of benefits, co-morbid conditions and disease severity), and physician
characteristics (specialty, metropolitan location), were summarized by the child's index bipolar diagnosis subtype. In addition to these descriptive summaries, changes in patients' bipolar diagnoses were tracked over the one year follow-up period. This allowed us to identify the extent to which initial bipolar diagnoses were stable in this population. Finally, we were able to summarize comorbid mental health conditions as occurring prior to initial diagnosis (pre-morbid) or occurring post initial diagnosis (post-morbid).
Drug classes were summarized in several ways using this study design. Because we were able to identify new users, initially prescribed therapies were summarized at the drug class level and by specific drug within each class for each disorder subtype. Initially prescribed therapies were defined in two ways: (1) medications used within 30 days of diagnosis, and (2) medications used within 90 days of diagnosis. Polypharmacy was assessed by identifying the number of drugs used over the selected timeframe. Specific drug use was captured as the number of prescriptions for each specific agent within a class over the
selected timeframes. For this analysis, fills were standardized to a 30 day supply to allow for comparisons of use across agents.
Drug class use within the year following index diagnosis was also summarized. This is presented as the number of agents used in the first year from index diagnosis (count of medications) as well as the frequency of use for each drug class. Use of psychotherapy and electroconvulsive therapy was also assessed for each bipolar subtype by identifying any use, and the frequency of use among users. Finally, payments made for treatment were
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summarized for both patients alone, and patients and insurers combined. These summaries included estimates of the median and mean payments for medical care among all patients and then separately among users of services.
3.6.2 Aim 2: Determine the factors associated with receiving a single mood stabilizer or