The Bipolar Disorder Knowledge Scale has demonstrated consistency and reliability between tests and retests for evaluating knowledge of bipolar disease, according to a study published in the Journal of Affective Disorders. 

Researchers sent a survey test to 43 pharmacists and 250 individuals from the general population who were recruited online. The participants answered questions about their health literacy, education, status of bipolar disorder diagnosis, and exposure to individuals with bipolar disorder before completing the 47-question scale. After 2 days, 100 members of the same general population group were surveyed to evaluate reliability of testing and retesting. The mean score on the Bipolar Disorder Knowledge Scale was 34.48 (SD 5.50), or 71.83%. A Cronbach’s alpha of 0.773 resulted before analysis of items, and 22 of 47 items were dropped following analysis of items. These final items ranked above 20% on a discrimination index and below 90% on a difficulty index. 

With 25 items remaining, the mean score among pharmacists was 23.20 (SD 1.36), or 92.8%, and 18.40 (SD 4.13), or 73.6%, for members of the general population (P<.001). A final Cronbach’s alpha of 0.760 indicated a significant standard of internal consistency. The reduced alpha value is likely due to a lower number of items on the scale. Those who performed a test and retest showed a Pearson Correlation of 0.841 (P<.001), which demonstrates significant reliability for testing and retesting.

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Results from Cronbach’s alpha, the difficulty index, and the discrimination index determined the items removed from the scale. To examine whether experts outperformed their counterparts on the scale, an unpaired t-test was used to evaluate the general public’s final scores in comparison with pharmacists’ scores.

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The study researchers conclude that “the [Bipolar Disorder Knowledge Scale] is a 25-item true-false scale that takes approximately 5-10 min to complete. The scale assesses knowledge of [bipolar disorder] with items targeting diagnosis, etiology, disease course, symptoms, treatment, and life impact. The scale has shown strong internal consistency and test-retest reliability in a general population and will be useful for evaluating knowledge of [bipolar disorder] as it relates to stigma, non-adherence, and other variables.”


Stump TA, Eng ML. The development and psychometric properties of the bipolar disorders knowledge scale. J Affect Disord. 2018 Jun 26;238:645-650.

This article originally appeared on Psychiatry Advisor