The Clinical History and Costs Associated With Delayed Diagnosis of Bipolar Disorder

Paul E. Stang, PhD; Cathy Frank, MD; Anupama Kalsekar, MS; Marianne Ulcickas Yood, DSc, MPH; Karen Wells, BS; Steven Burch, PhD

Disclosures
In This Article

Results

We identified 1084 patients with a bipolar disorder code recorded during the study period and 5420 comparison cohort patients. At their index visit, 82.4% of the bipolar disorder cohort was seen by the psychiatry department, 4.0% by primary care, and 1.8% in the emergency department. Most of the patients in this study had been enrolled in the health plan for a substantial time before bipolar diagnosis: 50% had been enrolled for 9 or more years, 24% for 5 to 9 years, 17% for 2 to 5 years, and 9.2% for 1 to 2 years.

The sociodemographics of the bipolar cohort with complete medical and pharmacy linkage are presented in Table 1 . Notably, the cohort is 62% female, 75% are between 18 to 54 years of age, and 64% are White. Age is directly related to time between first mental health encounter and bipolar diagnosis, with 56% of patients younger than 17 years of age (vs 18% of those age 55 to 64) diagnosed within 6 months of initial mental health presentation. More than 50% of patients older than 35 years of age were diagnosed with bipolar disorder after at least 2 years with a previous mental health diagnosis. There were no striking differences in time to bipolar diagnosis by race or gender ( Table 1 ).

Among the cohort of patients with bipolar disorder, the median time between initial mental health diagnosis and diagnosis of bipolar disorder was 21 months (95% CI, 18-24 months) with 33% of subjects receiving a bipolar diagnosis within 6 months of their initial mental health diagnosis. Almost half (47%) of the remaining patients with bipolar disorder did not receive their diagnosis for at least 4 years from the time of their initial mental health presentation. The median time to a diagnosis of bipolar disorder differed by initial mental health diagnosis recorded in the encounter databases: a median of 1.3 years in patients first presenting with depression, 2.1 years among patients with anxiety, 2.8 years among patients with schizophrenia, and 1.6 years among those with substance abuse. Overall, 25% of subjects with a recorded mental health diagnosis were followed for more than 4 years before receiving a diagnosis of bipolar disorder. One in 4 patients initially diagnosed with depression were followed for more than 3.3 years before receiving a bipolar diagnosis; similarly, 25% of the patients initially diagnosed with anxiety were followed for 4.9 years before bipolar diagnosis, as were 25% of those initially diagnosed with schizophrenia (4.8 years) and substance abuse (4.3 years).

Number of Antidepressants

Overall, 60% of the bipolar cohort had received at least 1 antidepressant prescription before diagnosis of bipolar disorder. By contrast, 13% of the matched comparison cohort filled an antidepressant prescription during the study period. The likelihood of filling a prescription for an antidepressant and the number of different antidepressants prescribed increased with increasing time between first mental health diagnosis and ICD-9 coded diagnosis of bipolar disorder ( Table 2 ); 11.0% of all patients with bipolar disorder (vs 0.4% of comparison group) received 4 or more antidepressants before their bipolar diagnosis. When the lag time from initial mental health diagnosis to bipolar diagnosis was at least 4 years, almost 23% of patients with bipolar disorder received at least 4 different antidepressants, and took antidepressants during 21.1% of their pre-diagnosis time. Among patients in the comparison group, 1.0% of those followed for at least 4 years before the index date received at least 4 different antidepressants, spending 2.2% of pre-index date time on antidepressant medication.

The Costs and Utilization of Services

Overall, patients with bipolar disorder had twice the number of interactions with the healthcare system before the index date than the non-bipolar comparison group. More specifically, patients diagnosed with bipolar disorder had 3 times the number of non-mental health hospitalizations, 3 times the number of emergency department visits, and 14 times the number of outpatient mental health visits than did the comparison cohort before the index diagnosis. Mean utilization following bipolar diagnosis was 16.5 outpatient encounters, 1.2 emergency department visits, and 0.4 inpatient hospitalizations per year, and the pre-diagnosis trend continued during the year after the index date.

Individuals diagnosed with bipolar disorder continued with twice the intensity of healthcare interactions overall, 4 times the number of non-mental health hospitalizations, 2.4 times the rate of emergency department visits, and 25.7 times the mean number of outpatient mental health encounters as the non-bipolar comparators. These ratios varied somewhat by time to bipolar diagnosis but did not appear to follow any particular pattern. During this post-bipolar diagnosis period, mean costs continued to be 2 to 3 times higher in patients with bipolar disorder compared with the comparison cohort patients.

Mean monthly costs among the bipolar cohort were not strikingly different before and after bipolar diagnosis (Figure 1); however, several cost differences did reach statistical significance. The component costs of caring for the patient with bipolar disorder after diagnosis of bipolar disorder increased with the increase in time from initial mental health encounter to bipolar diagnosis; these results were statistically significant for emergency costs (P = .04) and pharmacy costs (P = .001) (Figure 2). The mean annual total costs for the patients with bipolar disorder in the year after diagnosis ranged from $6076 (among those with a 6-month lag to diagnosis) to $9496 (those with more than 4 years between the initial psychiatric diagnosis and bipolar diagnosis).

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