Comorbidity is the rule rather than the exception with psychiatric disorders and is consequently of great interest to both researchers and clinicians. However, many studies of psychiatric comorbidity have been based on lifetime prevalence with mixed-age samples, a practice that (1) biases the assessment of epidemiologic comorbidity and (2) creates the appearance of comorbidity even when disorders are randomly associated. This bias is what we refer to as pseudocomorbidity.
To clarify the source of the problem and to discuss strategies that might be adopted to deal hereafter with lifetime prevalence data.
A simulated example is presented to show that even when there is only random association between disorders, there will appear to be nonrandom comorbidity when lifetime prevalence is used with mixed-age samples. An actual example relating psychosis to phobia is presented to show the bias that can result and to illustrate one way of dealing with lifetime prevalence data.
Use of lifetime prevalence with mixed-age samples, used almost exclusively in psychiatric research, generates problematic results, especially when used for assessment of comorbidity, and should be viewed with some skepticism. Hereafter, we recommend that any future use of lifetime prevalence should require determination of the age of onset, even if only by retrospective report. Comorbidity then should be reported by age.
Register and get free email Table of Contents alerts, saved searches, PowerPoint downloads, CME quizzes, and more
Subscribe for full-text access to content from 1998 forward and a host of useful features
Activate your current subscription (AMA members and current subscribers)
Purchase Online Access to this article for 24 hours
Onset curves (logarithm of the odds of onset vs age [in years]) for psychosis and simple phobia, actual comorbid psychosis and simple phobia, and randomly comorbid psychosis and simple phobia. Ln indicates natural logarithm; p, probability.
Odds ratios of association between psychosis and simple phobia at varying ages compared with the odds ratio using lifetime prevalence to illustrate the bias that may occur when comorbidity is assessed by using lifetime prevalence.
Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
Thank you for submitting a comment on this article. It will be reviewed by JAMA Psychiatry editors. You will be notified when your comment has been published. Comments should not exceed 500 words of text and 10 references.
Do not submit personal medical questions or information that could identify a specific patient, questions about a particular case, or general inquiries to an author. Only content that has not been published, posted, or submitted elsewhere should be submitted. By submitting this Comment, you and any coauthors transfer copyright to the journal if your Comment is posted.
* = Required Field
Disclosure of Any Conflicts of Interest*
Indicate all relevant conflicts of interest of each author below, including all relevant financial interests, activities, and relationships within the past 3 years including, but not limited to, employment, affiliation, grants or funding, consultancies, honoraria or payment, speakers’ bureaus, stock ownership or options, expert testimony, royalties, donation of medical equipment, or patents planned, pending, or issued. If all authors have none, check "No potential conflicts or relevant financial interests" in the box below. Please also indicate any funding received in support of this work. The information will be posted with your response.
Some tools below are only available to our subscribers or users with an online account.
Download citation file:
Web of Science® Times Cited: 35
Customize your page view by dragging & repositioning the boxes below.
More Listings atJAMACareerCenter.com >
Users' Guides to the Medical Literature
All results at
and access these and other features:
Enter your username and email address. We'll send you a link to reset your password.
Enter your username and email address. We'll send instructions on how to reset your password to the email address we have on record.
Athens and Shibboleth are access management services that provide single sign-on to protected resources. They replace the multiple user names and passwords necessary to access subscription-based content with a single user name and password that can be entered once per session. It operates independently of a user's location or IP address. If your institution uses Athens or Shibboleth authentication, please contact your site administrator to receive your user name and password.