Development of a digestive health status instrument: tests of scaling assumptions, structure and reliability in a primary care population.
BACKGROUND
The absence of valid and reliable health status measures for functional gastrointestinal illness has limited research and patient care for this common group of disorders. A self-report survey has been developed.


METHODS
Initial development focused on extensive pre-testing of patients, primary care physicians and gastroenterologists. The disease-specific portion included the Rome criteria for dyspepsia subgroups and the Manning and Rome criteria for irritable bowel syndrome. The Short Form-36 was added. Psychometric analyses included techniques of multitrait scaling, scale internal consistency and criterion validation.


RESULTS
Six hundred and ninety patients presenting to their primary care physician for treatment of heartburn, abdominal pain or discomfort completed the 98 question survey. The disease-specific portion revealed five components including reflux, dysmotility, a two-domain bowel dysfunction complex, and a pain index. Internal consistency measures demonstrated good to excellent reliability. Scaling successes were observed on multitrait scaling. The disease-specific portion was reduced to 34 questions. Criterion validity was demonstrated with the correlation of the disease-specific questions to the SF-36.


CONCLUSIONS
The psychometric analyses lend credence to the concept of stomach and bowel symptom subgrouping as proposed by expert consensus. The psychometric properties of the five summated disease-specific scales compare favourably with standardized health status measures.
Shaw
M
M
Health Research Center, Park Nicollet Clinic, Institute for Research and Education, HealthSystem, Minneapolis, Minnesota 55416, USA.
Talley
N J
NJ
Adlis
S
S
Beebe
T
T
Tomshine
P
P
Healey
M
M
D000328:Adult; D003109:Colonic Diseases, Functional / Q000175:diagnosis* / Q000523:psychology; D005163:Factor Analysis, Statistical; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D011320:Primary Health Care; D011594:Psychometrics; D011788:Quality of Life; D011795:Surveys and Questionnaires