Table 1.
Baseline Demographic and Clinical Characteristics Among Knee Osteoarthritis (OA) Patients and Controlsa
| Characteristics | Knee OA Cohort N=510,605 |
Control Cohort N=510,605 |
P Valueg |
|---|---|---|---|
| Age, mean (SD) | 60.0 (12.2) | 59.1 (13.6) | <0.001 |
| Age Categories, n (%) | 1.000 | ||
| ≤44 years | 42,954 (8.4) | 42,954 (8.4) | |
| 45–54 years | 117,777 (23.1) | 117,777 (23.1) | |
| 55–64 years | 206,554 (40.5) | 206,554 (40.5) | |
| 65–74 years | 76,098 (14.9) | 76,098 (14.9) | |
| >74 years | 67,222 (13.2) | 67,222 (13.2) | |
| Female, n (%) | 296,157 (58.0) | 296,157 (58.0) | 1.000 |
| Payer, n (%) | 1.000 | ||
| Commercial | 363,190 (71.1) | 363,190 (71.1) | |
| Medicare | 147,415 (28.9) | 147,415 (28.9) | |
| US Geographic Region, n (%) | 1.000 | ||
| Northeast | 104,456 (20.5) | 104,456 (20.5) | |
| North central | 133,471 (26.1) | 133,471 (26.1) | |
| South | 209,217 (41.0) | 209,217 (41.0) | |
| West | 63,461 (12.4) | 63,461 (12.4) | |
| Deyo-Charlson Comorbidity Index (DCI),b mean (SD) | 0.9 (1.6) | 0.6 (1.3) | <0.001 |
| Comorbid Medical Conditions, n (%) | |||
| Hypertension | 244,016 (47.8) | 129,002 (25.3) | <0.001 |
| Hyperlipidemia | 211,819 (41.5) | 98,086 (19.2) | <0.001 |
| Coronary heart diseasec | 128,745 (25.2) | 82,574 (16.2) | <0.001 |
| Obesity | 115,110 (22.5) | 11,446 (2.2) | <0.001 |
| Respiratory diseased | 111,408 (21.8) | 62,856 (12.3) | <0.001 |
| Type 2 diabetes mellitus | 94,752 (18.6) | 50,218 (9.8) | <0.001 |
| Depression | 57,082 (11.2) | 17,919 (3.5) | <0.001 |
| Renal diseasee | 38,867 (7.6) | 17,020 (3.3) | <0.001 |
| Rheumatoid arthritisf | 15,122 (3.0) | 3988 (0.8) | <0.001 |
| Metabolic syndrome | 4321 (0.8) | 888 (0.2) | <0.001 |
Notes: aDemographic characteristics (age, gender, payer, and geographic region) were assessed on the index date. Clinical characteristics (DCI, comorbid medical conditions) were reported for the 2-year pre-index period. Knee osteoarthritis patients were directly matched to controls (1:1) on age category, sex, payer, and geographic region; bDCI is an aggregate measure of comorbidity, which is expressed as a numeric score based on the presence of select diagnoses for various chronic medical conditions; ccoronary heart disease includes the following conditions: arrhythmias, atherosclerosis, congestive heart failure, ischemic heart disease, and valve disorders; drespiratory disease includes the following conditions: acute respiratory disease, asthma, COPD, emphysema, and other chronic respiratory disorders; erenal disease includes the following conditions: acute kidney disease, chronic kidney disease, kidney failure, kidney stones, and nephrotic syndrome; frheumatoid arthritis includes rheumatoid arthritis and other inflammatory polyarthropathies; gstatistical significance was defined a priori as p<0.05. All significant p-values are bolded in table text.
Abbreviations: N, sample size; SD, standard deviation.