External Source:
Validating estimates of NCD prevalence | BMC Medicine | Volume 13, Issue 1, pp.

“Despite the substantial burden of NCDs around the world, it continues to be difficult to collect accurate information on their prevalence, particularly in areas that lack consistent or accessible health care. In part, this is due to inherent limitations in diagnosis these conditions […] This study has two main objectives; first, to develop a questionnaire based on self-reported signs and symptoms and apply an automated technique to estimate the prevalence of NCDs in low-resource settings and, second, to assess the performance of both the questionnaire and the analytical technique.”


Background: Easy-to-collect epidemiological information is critical for the more accurate estimation of the prevalence and burden of different non-communicable diseases around the world. Current measurement is restricted by limitations in existing measurement systems in the developing world and the lack of biometry tests for non-communicable diseases. Diagnosis based on self-reported signs and symptoms (“Symptomatic Diagnosis,” or SD) analyzed with computer-based algorithms may be a promising method for collecting timely and reliable information on non-communicable disease prevalence. The objective of this study was to develop and assess the performance of a symptom-based questionnaire to estimate prevalence of non-communicable diseases in low-resource areas.

Methods: As part of the Population Health Metrics Research Consortium study, we collected 1,379 questionnaires in Mexico from individuals who suffered from a non-communicable disease that had been diagnosed with gold standard diagnostic criteria or individuals who did not suffer from any of the 10 target conditions. To make the diagnosis of non-communicable diseases, we selected the Tariff method, a technique developed for verbal autopsy cause of death calculation. We assessed the performance of this instrument and analytical techniques at the individual and population levels.

Results: The questionnaire revealed that the information on health care experience retrieved achieved 66.1% (95% uncertainty interval [UI], 65.6-66.5%) chance corrected concordance with true diagnosis of non-communicable diseases using health care experience and 0.826 (95% UI, 0.818-0.834) accuracy in its ability to calculate fractions of different causes. SD is also capable of outperforming the current estimation techniques for conditions estimated by questionnaire-based methods.

Conclusions: SD is a viable method for producing estimates of the prevalence of non-communicable diseases in areas with low health information infrastructure. This technology can provide higher-resolution prevalence data, more flexible data collection, and potentially individual diagnoses for certain conditions.

This study was led by investigators at the Institute for Health Metrics & Evaluation (IHME), based at the University of Washington, in collaboration with researchers in Mexico.