Recommendations for deleting five personality disorders in the upcoming fifth edition of the Diagnostic and Statistical Manual, the gold standard for reference for psychiatrists, could result in false-negative diagnoses for millions of patients if the removal is approved by the American Psychiatry Association, according to a new study.

The DSM-5 is a reference that shapes psychiatric treatment and insurance decisions, and its revisions will affect millions of people for years to come, according to researchers against the recommendations to change the approach toward diagnosing personality disorders.

The study was published in the Journal of Clinical Psychiatry on Tuesday.

DSM-5 Personality and Personality Disorders work group recently recommended the removal of paranoid, schizoid, histrionic, narcissistic and dependent personality disorders as a way to reduce comorbidity among disorders.

However, lead author Mark Zimmerman, director of outpatient psychiatry at Rhode Island Hospital said that the removal recommendations had no evidence or data describing the impact this potential deletion could have on the overall prevalence of personality disorders.

Researchers also noted that although narcissistic personality disorder had been recommended for removal, the Work Group recently advised that narcissistic disorder should be kept. Zimmerman also pointed out that there was also no research to justify the Work Group’s reversal in deciding to retain narcissistic personality disorder.

Researchers said that changes to the DSM are supposed to be made only when there is enough evidence to support the modification.

"Despite assurances that only data-driven modification would be made, with each new edition of the DSM, we have witnessed repeated instances of changes being made in the absence of sufficient data demonstrating the new criteria is superior," Zimmerman said in a statement.

Zimmerman and his colleagues assessed the proposed changes of deleting five personality disorders in the upcoming DSM-5 by evaluating 2,150 psychiatric outpatients and found that more than a fourth were diagnosed with one of the 10 DSM-4 personality disorders. Researchers added that of all the patients diagnosed with personality disorders according to the last DSM-4 criteria, 59 patients would no longer be diagnosed if the changes were applied.

"The findings of the present study highlight our concerns about adopting changes in the diagnostic manual without adequate empirical evaluation beforehand. To be sure, there are problems with the classification of personality disorders, however, the identification of a problem is only the first step of a process resulting in a change to diagnostic criteria," Zimmerman said in a statement.

New criteria or diagnostic material clinically useful but less reliable and valid information will not improve the classification of personality disorders, researchers said.

"When it comes to revising the official diagnostic classification system, the guiding principle should be that criteria should not be changed in the absence of research demonstrating that the new approach is superior to the old in either validity or clinical utility, preferably both," Zimmerman said.