Differences in risk factors for neurophysiologically confirmed carpal tunnel syndrome and illness with similar symptoms but normal median nerve function: a case–control study

Table 5 Associations with non-occupational and occupational risk factors in stepwise regression models

Risk factor	NP+ve cases v controls^a		NP-ve cases v controls^a		NP+ve cases v NP-ve cases^a
	OR^b	(95% CI)	OR^b	(95% CI)	OR^b	(95% CI)
BMI (Kg/m ² )
<25	1				1
≥25 and <30	1.6	(1.1-2.1)			1.3	(0.9-1.9)
≥30	2.1	(1.6-2.9)			2.7	(1.9-3.9)
Smoking habits
Never smoked	1				1
Ex-smoker	1.1	(0.8-1.4)			1.2	(0.9-1.7)
Current smoker	0.6	(0.4-0.8)			0.8	(0.5-1.1)
Other disease ^c
Diabetes			0.7	(0.4-1.2)	1.6	(0.9-3.1)
Other arthritis					0.7	(0.5-1.0)
Mental health
Good	1		1
Intermediate	1.3	(0.9-1.7)	1.5	(1.1-2.0)
Poor	1.4	(1.0-1.9)	1.3	(0.9-1.8)
Number of somatic symptoms at least moderately distressing in past week
0			1		1
1			1.5	(1.1-2.2)	0.7	(0.4-1.0)
≥2			1.5	(1.1-2.1)	0.6	(0.4-0.9)
Physical activities in an average working day ^c
Use of keyboard or mouse for > 4 hours in total			1.4	(1.1-1.9)	0.6	(0.4-0.8)
Other repeated movements of wrist/fingers for > 4 hours in total	1.5	(1.1-1.9)	1.2	(0.9-1.6)
Repeated bending /straightening of elbow for > 1 hour in total			1.3	(0.9-1.7)
Work for >1 hour in total with tool(s) that made the hand or arm vibrate	2.4	(1.6-3.8)	1.6	(1.0-2.6)	1.4	(0.9-2.2)
Psychosocial risk factors ^c
Targets, bonuses or deadlines			0.8	(0.6-1.0)	1.2	(0.9-1.7)
Little support from supervisor or colleagues	1.6	(1.1-2.3)	1.9	(1.3-2.7)
Little choice in how or what work is done or in timetable and breaks	1.4	(1.1-2.0)	1.4	(1.0-1.9)

^aAnalyses were restricted to 1628 subjects (773 controls, 457 NP+ve cases and 398 NP-ve cases) who had held a paid job. Data on some non-occupational risk factors were missing for small numbers of cases and/or controls (see Table 3).
^bFor each of the three comparisons, risk estimates were derived from a final regression model incorporating sex, age (in 10-year strata), ethnicity, and the other variables for which results are presented.
^cRisk estimates are for those exposed to the risk factor relative to those unexposed.

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