A major strength of our study was that immune-related conditions were ascertained through medical diagnoses from hospital discharge records.
At-risk and high-risk medical conditions were ascertained using ICD-10-GM diagnosis codes recorded any time prior to the beginning of the 2009 calendar year.
Chronic conditions were ascertained in the IFLS-4 by asking whether participants had ever been diagnosed with any of the following conditions: physical disabilities, brain damage, vision problems, hearing problems, heart problems, or depression.
Lifestyle risk factors and chronic conditions were ascertained using standard symptom-based questions [10], while hypertension and BMI category based on measured values [11] are presented for longitudinal analysis only as these variables had minimal impact in cross-sectional analyses.
Most of the earlier studies that attempted to redefine BMI cutoff points in Asian populations relied on prevalence data, in which BMI and obesity-related conditions were ascertained at the same point in time.
More importantly, different conditions were ascertained with different levels of rigour; dementia, depression and hypertension by clinical assessment, but heart disease and stroke by self-report of medical diagnosis and visual and hearing impairment by self-reported impairment.
Prevalent CHD (a history of myocardial infarction or angina), stroke, and nonvascular chronic conditions were ascertained at phases 3, 5, and 7. A history of angina was identified via questionnaire and was corroborated with medical records, by abnormalities in a resting electrocardiogram (ECG), an exercise ECG, or a coronary angiogram.
Chronic conditions were ascertained by asking the elderly person if he/she had been diagnosed by a doctor with any of a list of 11 chronic problems (hypertension, heart disease, circulation problems, stroke, diabetes, chronic respiratory problems, arthritis, cancer, Parkinson's disease, genitourinary and gastrointestinal problems).
The presence of these conditions among study subjects was ascertained based on available diagnostic information, laboratory/exam values, and treatments/medications recorded anytime during the study period.
