Table 3

Definitions of physical demand of the job in the literature and their association with primary OA

Author, year	Site of OA	Survey population and method	Time period and unit of exposure	Definition of physical demand†	OR‡
†Italicised items are those statistically significant and counted in table 4.
‡OR = highest odds ratios reported: crude OR reported as statistically significant; adjusted OR statistically significant; **adjusted OR statistically significant, suggesting a dose-response profile.
(***)As above but statistical significance not reported.
OR reported as not statistically significant are not shown in the table.
Anderson JJ et al, 1988⁵	Knee	Population survey HANES Ix ray diagnosed OA Self administered questionnaire	All job titles during lifetime Exposure estimated by experts using job titles	Physical demand:	OR: 3.1**
				Sedentary
				Light work
				Medium work
				Heavy work
				Very heavy work
				Knee bending requirements:	OR: 3.5***
				None
				Some (1–50% of job titles)
				Much (⩾50% of job titles)

Coggon D et al, 1998¹³	Hip	Case-control study Patients listed for hip replacement because of OA Interview questionnaire	All jobs held for longer than a year since leaving school and up to 10 years before study Maximum level of exposure achieved	Lifting: for more than 10 times in average working week, for at least 10 years:
				<10 kg
				10–24 kg
				25–49 kg
				⩾50 kg	OR: 2.1**
				Number of years (0, 1–9, 10–19, ⩾20):
				Climbing >30 flights of stairs/day	OR: 1.7**
				Walking >2 miles/day
				Driving >4 h/day
				Squatting >1 h/day
				Kneeling >1 h/day
				Standing >2 h/day
				Sitting >2 h/day

Coggon D et al, 2000¹⁴	Hip	Case-control study Patients listed for hip replacement because of OA Interview questionnaire	All jobs held for longer than a year since leaving school and up to ten years before study Occupational activities performed for over one year	Lifting for more than 10 times in average working week:
				⩾10 kg.	OR: 1.7**
				⩾25 kg.	OR: 1.7**
				⩾50 kg.
				Kneeling >1 h/day	OR: 1.8**
				Squatting >1 h/day	OR: 2.3**
				Walking >2 miles/day	OR: 1.9**
				Standing or walking >2 h/day
				Sitting >2 h/day
				Driving >4 h/day
				Climbing ladder or stairs >30 times/day
				All results comparable between males and females
				All results comparable between males and females

Cooper C et al, 1994¹⁵	Knee	Case-control study Symptomatic, x ray diagnosed OA Interview questionnaire	Job held for the longest time before onset of symptoms Exposure in an average day	Squatting >30 min/day	OR: 6.9**
				Kneeling >30 min/day	OR: 3.4**
				Stairs climbing >10 flights of stairs/day	OR: 2.7**
				Lifting weights >25 kg
				Walking >2 miles/day
				Standing >2 h/day
				Sitting >2 h/day
				Driving >4 h/day

Croft P et al, 1992¹⁶	Hip	Case-control study Hip replacement or x ray diagnosed OA Interview questionnaire	Lifetime occupational history Number of years of exposure	Duration in years:
				Lifting weights >25 kg by hand: <1, 1–19, ⩾20	OR: 2.5**
				Standing >2 h/day: <20, 20–39, ⩾40	OR: 2.7***
				Sitting >2 h/day: <1, 1–19, ⩾20
				Bending >2 h/day: <1, 1–19, ⩾20
				Kneeling >30 min/day: <1, 1–19, ⩾20
				Walking >2 miles/day: <1, 1–19, ⩾20
				Walking rough ground >2 miles/day: <1, 1–19, ⩾20
				Climbing ladders: <1, 1–19, ⩾20
				Squatting >30 min/day: <1, ⩾1
				Running >1 h/day: <1, ⩾1
				Climbing >30 flights stairs/day: <1, ⩾1
				Driving > 4 h/day: <1, ⩾1

Felson DT et al, 1991⁶	Knee	Population survey Framingham cohortx ray diagnosed OA	Current occupation in six successive questionnaires (1948–61)Exposure estimated by experts using job titles	Physical demand:
				Sedentary: lifting <10lb; occasional walking-standing
				Light: lifting <20l.; frequent lifts10lb; frequent walking-standing
				Medium: as in “light” with lifts <50 lb
				Heavy: as in “light” with lifts <100 lb
				Very heavy: as in “light” with lifts 100+ lb
				+ knee bending /kneeling /crouching/crawling required in job	OR: 2.4**

Heliovaara M et al, 1993¹⁷	Hip	Population survey (cohort)Clinical diagnosis of OA Self-administered questionnaire	Last, present or previous occupation of longest duration (if not the last one) involving one of the factors Number of factors (stresses) summed (0 to5)	Lifting/carrying heavy objects
				Stooping/twisting/awkward posture
				Vibration whole body/equipment continuously repeated series movements
				Working speed determined by machine
				Total number of stresses:	OR: 2.9***

Holte H et al, 2000¹⁸	Any	National disability pensioners survey Clinically diagnosed OA	Occupation in year previous to disability pension Physical demand coded by experts	Manual, skilled and unskilled labour (heavy lifting and bending).	OR: 1.9**
Holte H et al, 2000¹⁸

Jacobsson B et al, 1987¹⁹	Hip	Case-control study Patients on waiting list for hip replacement Self-administered questionnaire	Having been subjected to a factor any time during life (yes/no)	Heavy labour	OR: 1.2*
				Heavy lifting	OR: 1.2*
				Much tractor driving	OR: 1.5*
				Much walking
				Much standing

Lau EC et al, 2000²⁰	Hip or knee	Case-control studyx ray diagnosed OA Interview questionnaire	Having been engaged in activities (with at least one physical demand) during the occupation held for the longest time(and at least one year) before onset of symptoms (yes/no)No marked difference between hip and knee	Climbing ⩾15 flights of stairs/day	OR: 5.1**
				Lifting ⩾10 kg, >10 times/week	OR: 5.4**
				Use vibration tools ⩾1 h/day	(No marked difference between hip and knee)
				Walking ⩾2 h/day
				Squatting ⩾1 h/day
				Kneeling ⩾1 h/day
				Driving ⩾4 h/day

Manninen P et al, 2002²¹	Knee	Case-control study Patients with first knee arthroplasty Interview questionnaire	Average exposure in jobs held up to age 49	Physical workload :
				Sweating/rapid heart beat: Frequent	OR: 2.0***
				Occasional
				Not at all
				Standing: almost all the time
				> half of average work day
				< half an average work day
				Kneeling/squatting: >4 h/day	OR: 1.7**
				2–4 h/day
				<2 h/day
				not at all
				Climbing: much	OR: 1.6**
				some
				none or very little
			Cumulative exposure summed for all jobs up to age 49	Regular walking: average km/week
				Regular lifting: average weight × no. lifts/day
				Regular driving: average h/day or week

Olsen O et al, 1994²²	Hip	Case-control study Recipients of a hip prosthesis Telephone interview questionnaire	Cumulative exposures summed from the start of the occupational career to age 49 or the year of OA diagnosis	Lifting: kg/week
Olsen O et al, 1994²²				Number of lifts >40 kg/week	OR: 2.5(***)
				Static & dynamic work (not defined): h/week	OR: 2.4(***)
				Jumping : no. jumps/week

Roach KE et al, 1994²³	Hip	Case-control study Outpatient symptomatic OA Self-administered questionnaire	Cumulative lifetime exposure, as the sum number of years exposed to physical demands, on average more than half of their work day. Individual classified positive if cumulative exposure greater or equal to 15 years	Heavy workload:	OR: 2.4***
Roach KE et al, 1994²³				Heavy work standing
				Work walking
				Work kneeling/crouching
				Light workload: if no heavy workload and:
				Light work standing
				Work sitting
				Intermediate workload: all other than the above

Sandmark H et al, 2000²⁴	Knee	Case-control study Patients with prosthetic surgery due to primary tibiofemoral OA Telephone interview questionnaire	Cumulative lifetime exposure from age 15 to50. Sum of duration or frequency divided in quartiles of exposure	Kneeling: h/day	OR: 1.6**
				Squatting/bending: no./day	OR: 2.0**
				Jumping: no./day	OR: 2.0***
				Standing: h/day
				Sitting: h/day
				Whole body vibrations: h/day
				Climbing: no. stairs/day
				Lifting: kg × no. lifts/day

Schouten JSAG et al, 1992²⁵	Knee	Population survey–cohort followed for 12 yearsx ray defined OA Self-administered questionnaire.	Cumulative lifetime exposure. Score computed as intensity (not defined) of exposure times duration in years summed over all jobs with the exposure. Scores divided in tertiles (low, medium, high)	Lifting heavy objects
				Knocking one’s knee
				Walking
				Standing	OR: 3.8**
				Squatting
				Kneeling
				Crawling

Thelin A et al, 1997²⁶	Hip	Case-control studyx ray diagnosed OA Self-administered questionnaire	Full time working with what they themselves regarded as heavy physical work for a period longer than half a year before 16 years of age	Heavy physical work at young age	OR: 2.1*
Thelin A et al, 1997²⁶


Vingard E et al, 1991²⁷	Hip	Case-control study Recipients of hip prosthesis Interview and self-administered questionnaires	Cumulative exposure calculated separately in three categories: from start of career to age 29, from age 30 to 49 and over the age of 49. Exposure expressed as summed duration or frequency reported. No difference between age categories	Dynamic workload (all below):	OR: 2.2**
				Lifting: kg/week;	OR: 1.8**
				no. lifts>40 kg/week	OR: 2.4**
				Jumping: no. jumps/week
				Walking with burden: h/week
				Stairs climbing: h/week
				Static workload (all below):	OR: 2.9**
				Standing: h/week
				Sitting: h/week
				Biking: h/week
				Driving: h/week
				Twisted position: h/week

Vingard E et al, 1991⁷	Hip or knee	Register-based Population cohort study Hospital care for OA	Occupation within 10 years of hospital admission for OA Exposure estimated by experts using job titles and expressed as high or low dynamic or static forces (not defined) acting on the lower extremity	Blue collar with dynamic forces and/or static compression:
Vingard E et al, 1991⁷	Hip or knee			“High” versus “low”:
				Hip	OR: 2.2*
				Knee	OR: 1.9*

Vingard E et al, 1997²⁸	Hip	Register-based case- control study Women who underwent total hip replacement for primary OA Interview questionnaire	Cumulative exposure between the age of 16 to 50. Sum of duration of exposure or number of lifts times the weight lifted in an average working week.	Sitting: h/day
				Standing: h/day
				Working in twisted posture: h/day
				Lifting: 1–5 kg
				6–10 kg
				11–15 kg
				16–20 kg
				Jumping/movements between different levels: no./week	OR: 2.1**
				Climbing: no. flights of stairs/week	OR: 2.1**

Yoshimura N et al, 2000²⁹	Hip	Case-control study Patients listed for total hip arthroplasty due to OA Interview questionnaire	Exposure in first job and main job (not defined) defined as a job regularly involving each of the physical demand (yes/no). Little difference was found between the results on first job and main job	Lifting: ⩾10 kg more than once/week
				⩾25 kg more than once/week
				⩾50 kg more than once/week	OR: 4.1**
				Sitting ⩾2 h/?
				Standing ⩾2 h/?
				Kneeling ⩾1 h/?
				Squatting ⩾1 h/?
				Driving ⩾4 h/?
				Walking ⩾3 km/?
				Climbing ⩾30 flights of stairs/?