Only 40 percent of clinicians make a correct diagnosis of bipolar disorder when presented with a definitive case and are subject to heuristic (problem-solving by trial and error) bias, a survey shows.
Clinicians were more likely to make a correct diagnosis when more symptoms were present – meaning patients who just meet the threshold criteria are at risk for undertreatment, according to Larissa Wolkenstein, Ph.D. (University of Tübingen, Germany) and colleagues.
“Given the high prevalence and the high suicidal risk of bipolar disorder, it seems essential that clinicians are well-trained to diagnose bipolar disorder correctly,” the researchers said in the Journal of Affective Disorders.
Some studies have shown heuristic bias in bipolar disorder diagnosis, for example giving disproportionate weight to certain “prototypic symptoms” such as reduced need for sleep.
To investigate further, the researchers presented a case vignette that fulfilled the criteria for bipolar disorder to 204 psychotherapists.
The basic vignette was a patient who presented with depression and evidence of three out of the seven possible symptoms of hypomania (elevated, energetic and irritable mood, but not fully manic) on the DSM-IV. This was modified to include an additional fourth hypomanic symptom of reduced need for sleep or distractibility – thus giving three variant vignettes.
In addition, half of all vignettes included a potential casual explanation for hypomania – meeting a new partner (which does not preclude a diagnosis on the DSM-IV).
Overall, bipolar disorder was correctly diagnosed in 41.0 of the cases; in 59.0 percent of the cases another diagnosis was made, mainly unipolar depression (50.3 percent). Seven (3.8 percent) of those therapists, however, made a note indicating that they suspected a diagnosis of bipolar disorder.
Analysis showed that case vignettes with four hypomanic symptoms were more often diagnosed correctly (for reduced sleep, 47.3 percent, and distractibility, 57 percent) than were those with only the basic three symptoms (20 percent), giving a significant odds ratio for misdiagnosis of 5.5, when only the basic three symptoms were present.
There was a borderline significant trend for a causal influence on diagnosis, such that vignettes where the case reported recently meeting a new partner were slightly less likely to be correctly diagnosed as having bipolar disorder.
Finally, the study found that clinicians who misdiagnosed were less likely to recommend appropriate medication.
“Given that therapeutic strategies depend on the assigned diagnostic label, which might not only be inefficient but even harmful when making a wrong diagnostic decision, it becomes clear that a standardized diagnostic proceeding is in great demand,” the researchers said.