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Table 5 Main factors associated with participation in research clinics compared with observed target population.

From: The Knee Clinical Assessment Study – CAS(K). A prospective study of knee pain and knee osteoarthritis in the general population: baseline recruitment and retention at 18 months

 

Reported knee pain in last 12 months

Attended research clinic

OR (95%CI)

N*

3106

819

 

Practice

   

   A (ref.)

1227

302

1

   B

1251

330

1.10 (0.92, 1.31)

   C

628

187

1.30 (1.05, 1.61)

Age (years):

   

   50–59 (ref.)

898

236

1

   60–69

964

312

1.34 (1.10, 1.64)

   70–79

822

222

1.04 (0.84, 1.29)

   80+

422

49

0.37 (0.26, 0.51)

Gender:

   

   Female (ref.)

1832

440

1

   Male

1274

379

1.34 (1.14, 1.57)

Marital status:

   

   Married (ref.)

1985

599

1

   Divorced/separated

219

45

0.60 (0.43, 0.84)

   Widowed

705

137

0.56 (0.45, 0.69)

   Single

153

27

0.50 (0.32, 0.76)

Higher education:

   

   Yes (ref.)

327

117

1

   No

2685

684

0.61 (0.48, 0.78)

Occupational class†:

   

   Non-manual (ref.)

736

301

1

   Manual

1904

420

0.41 (0.34, 0.49)

Baseline HAD Anxiety:

   

   None (0–7) (ref.)

1656

500

1

   Possible (8–11)

842

217

0.80 (0.67, 0.97)

   Probable (12+)

508

85

0.46 (0.36, 0.60)

Baseline HAD Depression:

   

   None (0–7) (ref.)

2198

663

1

   Possible (8–11)

593

102

0.48 (0.38, 0.61)

   Probable (12+)

221

37

0.47 (0.32, 0.67)

  1. * – individual items may not add to totals due to missing data
  2. † – non-manual consists of higher managerial, higher professional, lower managerial/professional, and intermediate occupations; manual consists of lower supervisory/technical, semi-routine, and routine occupations. Self-employed have been excluded.