APPENDIX B

Measurement Issues in Calculating the Global Burden of Disease

Official health statistics are the source of information for estimates of the global burden of disease. However, these statistics from developing countries are frequently incomplete, inaccurate, or out of date, and they rarely contain adequate information on neurological, psychiatric, or developmental disorders. At the same time these data provide the best starting point for understanding the magnitude of the burden of disease and for confronting the needs imposed by that burden.

In addition to mortality statistics, disability-adjusted life year (DALY) calculations require numerical inputs for the specific incidence of disease, the proportion of disease incidence leading to disability, the average age of disability onset, the duration of disability, and the distribution of disability across six levels of severity. Because such data are often unavailable, determinations of burden typically incorporate estimates for most of these values. The potential limitations and sources of errors in DALY estimates include:

  • Disability-weights are presumed to be universal, but empirical studies are needed to validate these assumptions.

  • Limitations in the data needed from countries to estimate the burden of disease. The cause of death age and gender are needed, but only about 30-40% of all deaths are captured by vital registration in most developing countries.

  • The inability to quantify the contribution of risk factors in total burden of disease.

  • The value choices that underlie the definition of the DALY are not universally accepted.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 391
Neurological, Psychiatric, and Developmental Disorders: Meeting the Challenge in the Developing World APPENDIX B Measurement Issues in Calculating the Global Burden of Disease Official health statistics are the source of information for estimates of the global burden of disease. However, these statistics from developing countries are frequently incomplete, inaccurate, or out of date, and they rarely contain adequate information on neurological, psychiatric, or developmental disorders. At the same time these data provide the best starting point for understanding the magnitude of the burden of disease and for confronting the needs imposed by that burden. In addition to mortality statistics, disability-adjusted life year (DALY) calculations require numerical inputs for the specific incidence of disease, the proportion of disease incidence leading to disability, the average age of disability onset, the duration of disability, and the distribution of disability across six levels of severity. Because such data are often unavailable, determinations of burden typically incorporate estimates for most of these values. The potential limitations and sources of errors in DALY estimates include: Disability-weights are presumed to be universal, but empirical studies are needed to validate these assumptions. Limitations in the data needed from countries to estimate the burden of disease. The cause of death age and gender are needed, but only about 30-40% of all deaths are captured by vital registration in most developing countries. The inability to quantify the contribution of risk factors in total burden of disease. The value choices that underlie the definition of the DALY are not universally accepted.

OCR for page 391
Neurological, Psychiatric, and Developmental Disorders: Meeting the Challenge in the Developing World The DALY does not reflect individuals' ability to cope with their functional limitations. Estimations may exclude some disabilities, which leads to an underestimation of years lived with disability (e.g., childhood disabilities such as blindness or cognitive deficit), while some comorbidities might not be recognized (e.g., depression and substance abuse), leading to an overestimation or double-counting. Improving DALY measurements will require better data collection and analysis. Specific improvements might include: Validation of the methods to measure the time lived with disability of different severity; More accurate monitoring systems to be able to generate real estimates of mortality and disability by cause; and Projection methods that incorporate known levels and trends of major risk factors such as smoking and trends in other diseases. The lack of data on psychiatric disorders in many countries has led to estimates based on methods that might not be transferable to assess the health status of the global poor. Further work is needed on standardizing assessment indicators to obtain a more realistic view of the burden of disease affecting developing countries.