Prevalence of interstitial cystitis in first-degree relatives of patients with interstitial cystitis.
OBJECTIVE
To compare, in a pilot study, the prevalence of interstitial cystitis (IC) among first-degree relatives of patients with IC with the prevalence of IC in the general population. Often the first evidence that a disease may have a genetic susceptibility is the demonstration of family aggregation of the disease.


METHODS
Members of the Interstitial Cystitis Association (ICA) were mailed a survey inquiring about the prevalence of the disease or consistent symptoms in first-degree family members (parents, siblings, and/or children). The same survey instrument was used in telephone interviews of a randomly selected sample of nonrespondents to determine the degree of responder bias.


RESULTS
Of 2581 respondents to the mail-in survey, 101 (3.9%) reported 107 first-degree relatives with IC. The subsequent telephone interviews with 346 randomly selected nonrespondents revealed little selection bias in the mail-in survey. These measurements, plus data-based assumptions of proportions of those self-reporting IC who actually met the hydrodistension requirements for the diagnosis of IC, suggest that women, 31 to 73 years old who were first-degree relatives of patients with IC, themselves had a prevalence of IC of 995/100,000. A comparison of this with the number approximating the prevalence in the general population of American women of this age (60/100,000) indicates a risk ratio for IC in adult female first-degree relatives of 17.


CONCLUSIONS
Adult female first-degree relatives of patients with IC may have a prevalence of IC 17 times that found in the general population. This, together with previously reported evidence showing a greater concordance of IC among monozygotic than dizygotic twins, suggests, but does not prove, a genetic susceptibility to IC.
Warren
John W
JW
Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
Jackson
Theresa L
TL
Langenberg
Patricia
P
Meyers
Deborah J
DJ
Xu
Jianfeng
J
D000328:Adult; D000368:Aged; D018856:Cystitis, Interstitial / Q000453:epidemiology / Q000235:genetics*; D005192:Family Health; D005260:Female; D020022:Genetic Predisposition to Disease; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D015995:Prevalence; D012306:Risk; D011795:Surveys and Questionnaires