rates of medical utilization but do not utilize me ntal health services more than the general
population. They often consult multiple physi cians for the same problem and obtain re-
peatedly negative diagnostic te st results. At times, medical attention leads to a paradoxical
exacerbation of anxiety or to iatrogenic complications from diagnostic tests and proce-
dures. Individuals with the disorder are genera lly dissatisfied with their medical care and
find it unhelpful, often feelin g they are not being taken seriously by physicians. At times,
these concerns may be justif ied, since physicians sometimes are dismissive or respond
with frustration or hostility. Th is response can occasionally result in a failure to diagnose
a medical condition that is present.
Prevalence
Prevalence estimates of illness anxiety disorder  are based on estimates of the DSM-III and
DSM-IV diagnosis hypochondriasis.  The 1- to 2-year prevalen ce of health anxiety and/or
disease conviction in community surveys and population-based samp les ranges from 1.3%
to 10%. In ambulatory medica l populations, the 6-month/1-ye ar prevalence rates are be-
tween 3% and 8%. The prevalence of the disorder is similar in  males and females.
Development and Course 
The development and course of illness anxiety disorder are unclear. Illness anxiety disor-
der is generally thought to be a chronic and relapsing condition with an age at onset in
early and middle adulthood. In population-b ased samples, health -related anxiety in-
creases with age, but the ages of individuals with high health anxi ety in medical settings
do not appear to differ from those of other patients in those settings. In older individuals,