CASE: Unclear diagnosis
Police find Ms. S, age 31, extremely intoxicated and drinking alcohol in her car in a city park parking lot. In the emergency room, she becomes increasingly somnolent and clinicians intubate her trachea to protect her airway. Lab testing shows she has elevated acetaminophen and lithium serum levels, and she is transferred to our hospital for further management after being started on N-acetylcysteine to treat acetaminophen toxicity. Her “ex-fiancé,” the father of her 2 children, saw her earlier the day of the episode and says she was distraught, intoxicated, and had several empty pill bottles in her purse.
In our hospital, Ms. S’ lithium level increases from 2.3 mEq/L to a peak of 5.32 mEq/L, and she undergoes hemodialysis. On hospital day 2, her serum lithium level is trending downward. After Ms. S is able to breathe spontaneously, her trachea is extubated and her hemodialysis line is removed. A psychiatric consultation is obtained, but she is unable to provide a coherent history and the treating clinicians believe she has delirium caused by multiple factors.
On hospital day 3, Ms. S’ delirium clears enough for her to engage in an interview, and she is transferred to our inpatient psychiatry ward for further monitoring and stabilization.
She reports that she was diagnosed with bipolar disorder (BD) at age 12, when she faced multiple psychosocial stressors, including physical abuse by her mother’s boyfriend. She took several psychotropics—although she cannot remember which ones—until age 14, when she stopped all medications until the year before her current hospitalization. Although throughout adolescence and adulthood Ms. S experienced chronic irritability, anxiety, impulsive behavior, poor self-esteem, abusive relationships, self-cutting, and depressed mood, she maintains that she felt worse when she was taking psychotropics and doubts the BD diagnosis. She attributes her longstanding mood issues to low self-worth, a “codependent nature,” and a tendency to gravitate toward abusive relationships. Although she admits to experimenting with several illicit drugs during adolescence, she denies more recent substance use and states she drinks alcohol only once every few months.
The authors’ observations
BD is underdiagnosed in several patient populations, such as individuals previously diagnosed with MDD.1-3 Misdiagnosis can have severe implications, including delay in receiving treatment with effective medications (eg, mood stabilizers) or use of agents that can induce mania or rapid-cycling, such as antidepressants. Perhaps in response to this concern, in recent years clinicians increasingly have diagnosed BD in adolescents and adults. An analysis of a national database of physician practices found a 40-fold increase in office visits for BD among youth and a near doubling among adults from 1994 to 2003.4
Although underdiagnosis of BD remains important, some researchers have suggested that overdiagnosis may be more prevalent and equally harmful. In a study of 180 patients being treated for depression in a family care clinic, there was a 21.6% initial underdiagnosis rate among those eventually found to have BD.1 However, among 43 patients with a prior BD diagnosis, the diagnosis was not confirmed in 33%.1 In a study of 700 psychiatric outpatients in Rhode Island, only 43% of 145 patients who reported a prior BD diagnosis had that diagnosis confirmed.5 Three times as many patients were overdiagnosed with BD as underdiagnosed.
Are there characteristics common to individuals incorrectly diagnosed with BD? In a study that compared patients who had been mistakenly diagnosed with BD with those who had not been diagnosed with BD, the overdiagnosis group was significantly more likely to be diagnosed with a personality disorder, in particular borderline or antisocial personality disorder.6 Only lifetime and current BPD, current posttraumatic stress disorder (PTSD), and lifetime impulse control disorders were independently associated with BD overdiagnosis. The odds ratio for overdiagnosis of BD in patients found to have BPD was 3.7.
EVALUATION: Rethink the diagnosis
In the last few months, Ms. S had complained to her primary care provider (PCP) of worsening anxiety and depressed mood. She was the victim of ongoing physical and emotional abuse by her ex-fiancé and was concerned that she may lose custody of her 2 sons. Approximately 8 months before admission, Ms. S’ PCP prescribed lithium, 450 mg, 3 times a day, for “mood stabilization” and depression because she’d already been diagnosed with BD. This was the first mood stabilizer she’d taken since she was 14. She also was taking unknown doses of hydrocodone/acetaminophen, cyclobenzaprine, and tramadol for pain and temazepam for insomnia. Ms. S continued to suffer from labile and depressed mood, and fought with her ex-fiancé and legal authorities to maintain custody of her 2 children until she was found in the park.