The use of count data models in biomedical informatics evaluation research

• Published in: Journal of the American Medical Informatics Association : JAMIA 2012-01, Vol.19 (1), p.39-44
• Main Authors: Du, Jing, Park, Young-Taek, Theera-Ampornpunt, Nawanan, McCullough, Jeffrey S, Speedie, Stuart M
• Format: Article
• Language: English
• Subjects: Biomedical Research - methods; Clinical Laboratory Techniques - statistics & numerical data; Electronic Health Records; Evaluation Studies as Topic; Humans; Least-Squares Analysis; Medical Informatics; Models, Statistical; Regression Analysis; Review
• ISSN: 1067-5027; 1527-974X
• DOI: 10.1136/amiajnl-2011-000256

Studies on the impact and value of health information technology (HIT) have often focused on outcome measures that are counts of such things as hospital admissions or the number of laboratory tests per patient. These measures with their highly skewed distributions (high frequency of 0s and 1s) are more appropriately analyzed with count data models than the much more frequently used variations of ordinary least squares (OLS). Use of a statistical procedure that does not properly fit the distribution of the data can result in significant findings being overlooked. The objective of this paper is to encourage greater use of count data models by demonstrating their utility with an example based on the authors' current work. Researchers conducting impact and outcome studies related to HIT. We review and discuss count data models and illustrate their value in comparison to OLS using an example from a study of the impact of an electronic health record (EHR) on laboratory test orders. The best count data model reveals significant relationships that OLS does not detect. We conclude that comprehensive model checking is highly recommended to identify the most appropriate analytic model when the dependent variable being examined contains count data. This strategy can lead to more valid and precise findings in HIT evaluation studies.