Increased BD prevalence in Australia
MedWire News: There has been a significant increase in the detection and prevalence of bipolar disorder (BD) among the population of Australia since 1998, study results suggest.
However, the team says that improved awareness and detection methods, rather than a true increase in BD, may be responsible for the findings.
"Early community-based studies estimated the lifetime prevalence of BD to be between 0.4% and 1.6%," explain Kerena Eckert (University of Adelaide, Australia) and team. "However, recent studies have reported lifetime prevalence rates of between 2.5% and 3.7%."
To investigate changes in the prevalence of BD in Australia in recent years, the team studied data from South Australian Health Omnibus Surveys (SAHOS) conducted in 1998, 2004, and 2008 among nationally representative samples of the population aged 15 years and older.
In total, 3010 individuals were interviewed in 1998, 3015 in 2004, and 3034 in 2008, with average ages of 43.9, 45.3, and 45.8 years, respectively.
Bipolar disorder was assessed using three methods: the mood module of the Primary Care Evaluation of Mental Disorders (PRIME-MD) at all three times points, a single unambiguous question on doctor-diagnosed BD from the PRIME-MD ("Did a doctor ever say you were manic depressive, have bipolar disorder, or give you lithium?") at all three time points , and the Mood Disorder Questionnaire (MDQ) in 2004 and 2008.
The researchers found that, according to PRIME-MD, there was a significant linear increase in the prevalence of BD over the study period, from 0.5% in 1998 to 1.0% in 2004 and 1.5% in 2008.
Similarly, positive answers to the question on doctor-diagnosed BD increased significantly over the study period, from 1.1% in 1998 to 1.7% in 2004 and 2.9% in 2008.
BD prevalence according to the MDQ also increased from 2.5% in 2004 to 3.3% in 2008, although this difference did not reach statistical significance.
Eckert and team conclude: "The present study demonstrates that on the basis of both the PRIME-MD algorithm and the single-question respondent-reported doctor diagnosis, there has been a significant increase in the prevalence of BD between 1998 and 2008."
They add: "These results add to the literature which indicates that there has been an increase in reported BD, but this may be due to incremental changes in diagnostic practices, rather than a true increase."
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By Mark Cowen