Related Experiment Video
Updated: Jul 7, 2026
Inverse Probability of Treatment Weighting (Propensity Score) using the Military Health System Data Repository and National Death Index
Published on: January 8, 2020
[Reliability of health insurance claim statistical data based on the principal diagnosis method]
Shinichi Tanihara1, Zentaro Yamagata, Hiroshi Une
1Department of Hygiene and Preventive Medicine, Faculty of Medicine, Fukuoka University, Japan. taniyan@fukuoka-u.ac.jp
Insights
The principal diagnosis method overestimates disease-specific medical expenses in Japan. Using multiple diagnoses provides a more accurate estimation of healthcare costs for conditions like hypertension and diabetes mellitus.
Area of Science:
- Health economics
- Medical informatics
- Public health
Context:
- Japanese National Health Insurance claims often include multiple diagnoses.
- Current methods assume all expenses relate to the principal diagnosis.
- This assumption may lead to inaccurate disease-specific expense estimations.
Purpose:
- To evaluate the validity of using only the principal diagnosis for estimating disease-specific medical expenses.
- To compare expense estimations using the principal diagnosis versus up to ten diagnoses.
Summary:
- Analyzed 8471 outpatient claims using International Classification of Diseases codes.
- Estimated disease-specific expenses using principal diagnosis only and up to ten diagnoses (Proportional Disease Magnitude method).
- Found significant differences in expense proportions, with the principal diagnosis method overestimating costs for conditions like hypertension.
Impact:
- The principal diagnosis method overestimates medical care expenses for frequently principal-diagnosed conditions.
- Accurate disease-specific expense data is crucial for health policy and resource allocation.
- This study highlights the need for improved methodologies in healthcare cost analysis.
Objective:
The estimation of disease-specific medical expenses in Japan is based on the assumption that all medical care expenses in a given claim are spent on the principal diagnosis even though health insurance claims actually include multiple diagnoses. The purpose of this study was therefore to evaluate the validity of this methodology.
Methods:
Medical expenses and the diagnosis based on the International Classification of Diseases, which are presently used for the Japanese National Health Insurance program, were obtained from 8471 outpatient medical expense claims from the National Health Insurance for Medical services for the Aged in Okaya city, Nagano Prefecture in May 2004. We calculated the frequency of each specific disease and estimated the disease-specific medical expenses using only the principal diagnosis in a claim and 10 diagnoses (principal diagnosis and nine additional diagnoses). Disease-specific medical expenses using 10 diagnoses was estimated according to the Proportional Disease Magnitude method.
Results:
The proportion that the principal diagnosis method reflected the frequency based on the method using ten diagnoses differed depending on the diagnosis. The proportion for hypertension was 59.7%, whereas it was 33.3% for diabetes mellitus. Hypertension and diabetes mellitus were estimated to be 18.32% and 5.38%, respectively, of all medical care expenses, as determined using the principal diagnosis method. However, when using ten diagnoses, hypertension and diabetes mellitus were estimated to be 8.50% and 5.16%, respectively, of all medical care expenses.
Conclusions:
The above described principal diagnosis method is therefore considered to overestimate the medical care expenses of diseases that are often selected as the principal diagnosis.
Related Concept Videos
01:10Documentation of Nursing Diagnosis
In some settings, data-driven computerized decision support systems are in place, allowing for more accurate nursing diagnoses. The database within one of these systems includes diagnostic labels defining characteristics, activities, and indicators for nursing. A nurse enters assessment...
01:25Statistical Methods for Analyzing Epidemiological Data
01:20Biostatistics: Overview
Discrete variables are...
01:16Statistical Inference Techniques in Hypothesis Testing: Parametric Versus Nonparametric Data
Parametric statistics, as the name suggests, assumes that data follow a specific distribution, often a normal distribution. This assumption enables robust hypothesis testing and estimation. Parametric methods, like the Student's t-test or Goodness-of-fit test, are frequently employed in biostatistics due to their robustness. For instance, comparing...
01:15Methods of Documentation VI: Case Management Model
For example, a patient with a chronic illness...
01:24Testing a Claim about Population Proportion
There are two methods of testing a claim about a population proportion: (1) Using the sample proportion from the data where a binomial distribution is approximated to the normal distribution and (2) Using the binomial probabilities calculated from the data.
The first method uses normal distribution as an approximation to the binomial distribution. The requirements are as follows: sample size is large...