Evidence-Based Cutoff Threshold Values from Receiver Operating Characteristic Curve Analysis for Knee Osteoarthritis in the 50-Year-Old Korean Population: Analysis of Big Data from the National Health Insurance Sharing Service

Figure 1

Diagram of the study design. A total of 514,866 patients enlisted in the NHISS were extracted. Patients with OA from the NHISS DB were subtracted by using KSCDCD-provided OA codes (M17, M17.1, M17.2, M17.3, M17.4, M17.5, M17.6, M17.7, M17.8, and M17.9), and patients with OA in this stage were those registered in the NHISS with a one-time diagnosis of OA. The age range of patients used to analyze the most OA pathogenic group was from 40 to 70 years. The effect of 4 independent variables (Walk30_Wek_Freq_ID, Mov20_Wek_Freq_ID, Mov30_Wek_ID, and Exerci_Freq_RSPS_ID) on 16 dependent variables (BMI, BP_High, BP_LWST, TOT_CHOLE, SGOT_AST, SGPT_ALT, Gamma_GTP, HCHK_PMH_CD2, WAIST, ELD_LLFX_SEC, ELD_LLFX_YN, STF_SEC, ELD_STFX_MTHD, and FALL) were verified by using univariate analysis of variance. Variables with statistical significance were selected and cutoff thresholds for optimal points were provided by using ROC curve analysis in 50-year-old patients with OA. OA, osteoarthritis; NHISS, National Health Insurance Sharing Service; KSCDCD, Korean Standard Classification of Disease and Causes of Death; Exerci_Freq_RSPS_CD, number of dates with exercise; Walk30_Wek_Freq_ID, number of dates with >30 min walking exercise in a week; Mov20_Wek_Freq_ID, number of dates with 20 min intensive exercise in a week; Mov30_Wek_Freq_ID, number of dates with 30 min moderate exercise in a week; BMI, body mass index; BP_High, maximal systolic blood pressure; BP_LWST, lowest diastolic blood pressure; ELD_LLFX_SEC, lower-extremity function assessing the time taken for walking 3 m away and back (only for 66 year olds); ELD_STFX_MTHD, balance test only for 66 year olds by taking the time of standing up with eyes closed or eyes opened; SGOT_AST, serum glutamic oxaloacetic transaminase and aspartate aminotransferase; SGPT_ALT, serum glutamate-pyruvate transaminase and alanine aminotransferase; TOT_CHOLE, total cholesterol.