Comorbidity in incident osteoarthritis cases and matched controls using electronic health record data

Table 1 Baseline characteristics of analysis set

	Cases N = 79,937	Controls N = 318,206
Age^a, median (IQR)	66.1 (57.4–74.8)	65.9 (57.3–74.6)
Sex, percentage female	64.0	64.0
Observational period^b, median (IQR)	2.9 (1.3–4.9)	3.2 (1.5–5.3)
BMI^c in kg/m², mean (SD) (available for 21% of analysis set)	29.0 (5.6)	27.9 (5.9)
Smoking status^c, percentages (available for 37% of analysis set)
Current	19.6	29.0
Never	49.1	46.8
Past	31.3	24.2
Alcohol^c units per day, mean (SD) (available for 13% of analysis set)	0.8 (1.6)	0.9 (1.7)

^aAge in years was calculated at the index date
^bObservational period in years counted from the start of the observational period until the index date
^cThe first recorded measure at, or after the start of the patients’ observational period was used. This corresponded best with the situation at baseline. Of BMI, smoking status, and alcohol use, there was only a limited availability of measurements in up to 37% of the analysis set

ISSN: 1478-6362