International Journal of Clinical Practice

Research Article

Chronic Low Back Pain with and without Concomitant Osteoarthritis: A Retrospective, Longitudinal Cohort Study of Patients in England

Table 1

Demographic and clinical characteristics of cases and general population controls.
CharacteristicCLBP aloneCLBP + OA
Cases (N = 13 554)Controls (N = 13 554)Cases (N = 7803)Controls (N = 7803)
Age at indexing†, years
Mean (SD)50.4 (16.0)50.4 (16.0)66.1 (11.9)66.1 (11.9)
≥65 years, n (%)2838 (20.9)2838 (20.9)4463 (57.2)4463 (57.2)
Sex†, n (%)
Male5374 (39.6)5374 (39.6)2478 (31.8)2478 (31.8)
Female8180 (60.4)8180 (60.4)5325 (68.2)5325 (68.2)
Mean BMI, kg/m2 (SD)29.2 (6.3)‡—30.6 (6.1)§—
Comorbid physical conditions‡, n (%)
Hypertension3480 (25.7)2766 (20.4)4225 (54.1)3154 (40.4)
Asthma2621 (19.3)2192 (16.2)1747 (22.4)1232 (15.8)
Hyperlipidaemia1818 (13.4)1125 (8.3)2333 (29.9)1286 (16.5)
Diabetes1031 (7.6)772 (5.7)1073 (13.8)831 (10.6)
Other CHD802 (5.9)469 (3.5)1109 (14.2)655 (8.4)
Comorbid mental health conditions, n (%)
Depression4785 (35.3)1745 (12.9)2824 (36.2)969 (12.4)
Anxiety2350 (17.3)888 (6.6)1451 (18.6)613 (7.9)
Mean CCI, lifetime value (SD)†0.83 (1.33)0.83 (1.33)1.34 (1.60)1.34 (1.60)
Length of follow-up, months
Mean (SD)43.6 (22.8)43.0 (22.5)39.9 (20.5)39.1 (20.3)
Mean time from diagnosis to indexing, years (SD)5.4 (5.3)§NA4.0 (4.3)NA
†Used to match cases to controls. ‡N = 5429 due to missing data. §N = 4044 due to missing data. Top five comorbidities recorded prior to indexing (from a prespecified list; not all possible comorbid conditions were assessed). §First instance of LBP diagnostic code within the patient’s medical record. Later of first instance of an OA or LBP diagnosis in the patient’s medical record.  < 0.05;  < 0.0001 versus controls. Abbreviations: BMI, body mass index; CCI, Charlson Comorbidity Index; CHD, coronary heart disease; CLBP, chronic lower back pain; GP, general practitioner; LBP, lower back pain; NA, not applicable; OA, osteoarthritis; SD, standard deviation.