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Validation of a case definition for speech and language disorders: In community-dwelling older adults in Alberta.

OBJECTIVE
To validate a case definition for speech and language disorders in community-dwelling older adults and to determine the prevalence of speech and language disorders in a primary care population.


DESIGN
This is a combined case definition validation and cross-sectional prevalence study. Chart review was considered the reference standard and was used to estimate prevalence. This study used de-identified electronic medical record data from participating SAPCReN-CPCSSN (Southern Alberta Primary Care Research Network-Canadian Primary Care Sentinel Surveillance Network) primary care clinics.


SETTING
Southern Alberta.


PARTICIPANTS
Men and women aged 55 years and older who had visited a SAPCReN-CPCSSN physician or nurse practitioner at least once in the 2 years before the beginning of the study.


MAIN OUTCOME MEASURES
Validation analysis included estimation of sensitivity, specificity, positive predictive value, and negative predictive value. Prevalence was the other main outcome measure.


RESULTS
The prevalence of speech and language disorders within the sample of 1384 patients was 1.2%. The case definition had a favourable specificity (99.9%, 95% CI 99.6% to 100.0%), positive predictive value (75.6%, 95% CI 25.4% to 96.6%), and negative predictive value (99.0%, 95% CI 98.8% to 99.2%). Sensitivity was not sufficient for validity (18.8%, 95% CI 4.05% to 45.6%).


CONCLUSION
The case definition did not meet an acceptable standard for validity and thus cannot be used for future epidemiologic research. However, owing to the case definition's high positive predictive value, it might be useful for clinical purposes and for cohort studies. Finally, while the case definition did not prove valid, this study has provided a conservative estimate of prevalence (1.2%) given the case definition's high specificity.