Read more: 鈥�鈥楲abel jars, not people鈥�: Lobbying against the shrinks鈥�
HOW reliable is reliable enough? When it comes to diagnosing mental illness, most people would want the bar set pretty high, which is why the latest revision of psychiatry鈥檚 diagnostic manual has become mired in controversy 鈥� again.
Last week, at its in Philadelphia, Pennsylvania, the American Psychiatric Association revealed results from of diagnoses proposed for the next edition of the APA鈥檚 Diagnostic and Statistical Manual of Mental Disorders, or . Essentially, the trials asked whether doctors would come to the same conclusions when assessing the same patients using the new diagnostic criteria.
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While for some diagnoses reliability was good, others yielded scores little better than chance. Already, the results have led to two proposed disorders being relegated to the volume鈥檚 appendix, which lists conditions that require further study. Critics argue that more might have joined them had the APA not adopted a low threshold for what is considered an acceptable score for reliability.
鈥淲hile for some diagnoses reliability was good, others yielded scores little better than chance鈥�
The conditions with questionable reliability include subtly altered descriptions of two of the most common diagnoses in psychiatry: and . That has opened a can of worms, leaving some mental health professionals wondering about the reliability of even established psychiatric diagnoses.
The final wording of DSM-5, scheduled for publication in May 2013, will have profound effects on people鈥檚 lives. The manual not only helps determine who is given psychoactive drugs, but in the US may determine whether treatment is covered by health insurance. Some diagnoses are even used to justify holding people indefinitely in secure mental hospitals.
The DSM-5 revision has been intensely controversial, with critics including , who led the most recent major rewrite in 1994, DSM-IV, charging that poorly drafted changes would lead to millions more people being given unnecessary and risky drugs (see 鈥淟abel jars, not people鈥�).
The field trials used a statistic called . This measures the consensus between different doctors assessing the same patient, with 1 corresponding to perfect diagnostic agreement, and 0 meaning concordance could just be due to chance. In January, leaders of the DSM-5 revision announced that kappas as low as 0.2 should be considered 鈥渁cceptable鈥� (, ).
鈥淢ost researchers agree that 0.2 to 0.4 is really not in the acceptable range,鈥� says of the University of Central Florida in Orlando, who is tracking DSM-5 for the American Counseling Association.
One proposed diagnosis failed to reach even this standard. Some patients turning up in doctors鈥� offices are both depressed and anxious, so was tested as a new category: the kappa for adults was less than 0.01.
, meanwhile, was intended to catch young people in the early stages of schizophrenia and other psychotic disorders. While field trials gave a kappa of 0.46, the variability was so large that , APA鈥檚 head of research, told the meeting that the result was 鈥渦ninterpretable鈥�.
Both disorders are now headed for DSM-5鈥榮 appendix, and Frances is especially relieved about attenuated psychosis syndrome. 鈥淚t would have exacerbated the already terrible problem of excessive and inappropriate antipsychotic use in kids,鈥� he says. But Frances remains worried about other proposals, including a system for diagnosing personality disorders that critics say is so complex that it is impractical.
Parents of children with autism and related disorders, meanwhile, are alarmed by a suggesting that many will lose their diagnosis 鈥� and with it the extra help they receive in school 鈥� under a new (Journal of the American Academy of Child & Adolescent Psychiatry, ). Regier argues that these fears are unfounded since the field trials did not highlight a dramatic drop in the number of people diagnosed.
Regier agrees, however, that the low kappas recorded for major depressive disorder and generalised anxiety disorder 鈥� 0.32 and 0.2 respectively in the adult trials 鈥� raise serious questions. He believes the problem is that depression and anxiety are 鈥渢he fevers of mental disorder鈥�, occurring as symptoms in a variety of conditions.
Maybe so, but if depression and anxiety can鈥檛 be reliably diagnosed, many patients will wonder how many more disorders stand on similarly shaky ground.
