Table 2.

Summary of the included studies.

Study	Subjects				Definition of neck pain	Prevalence
	n	Age, years	Country	Occupation
23	629	<30: 6%	Belgium	Office worker	‘Neck pain was defined as pain in the head and neck region, shades in a drawing of the head, neck and shoulder area’	53% (1 week); 65% (1 year); 78% (lifetime)
		30–39: 33%
		40–49: 49%
		>50: 11%
28	63	30 (24–39)	S Korea	Air Force pilot	Not specified	50.7% (1 year)
29	73	39 ± 8	Sweden	Air Force personnel	‘…any physical complaints or injuries during the previous 12 months and/or at present’	56% (1 year)
18	70	F-16: 32.54 ± 4.71	Italy	F-16 pilot: n = 35	‘Neck pain was defined as at least two episodes of neck pain after flight in the last 2 months’	48.6% for F-16 group (2 months)
		Typhoon: 33.37 ± 3.84		Typhoon pilot: n = 35		5.7% for Typhoon group (2 months)
22	19,673	≥ 40: 31.9%	USA	HPA pilot: n = 5681	‘…the primary diagnosis was related to a cervical or lumbar intervertebral disc bulge, disc herniation or protrusion, disc degeneration, and/or spondylosis’	0.52% (lifetime)
		≤ 39: 68.1%		RWA pilot: n = 719
				FWA pilot: n = 13273
26	221	44.7 ± 8.4	Austria	Helicopter pilots: n = 104	‘…we defined pain as any reported pain experience, ache or discomfort’	67.3% for helicopter pilots (1 year)
				Crew members: n = 117		45.3% for crew members (1 year)
30	184	< 30: 68.5%	Denmark	Army*	Not specified	36.4% (1 year)
		≥ 30: 31.5%
24	195	HQ: 39 ± 6	Finland	Military pilots	‘…cervical spine pain must have appeared after the commencement of active military flying…preclude prolonged or sustained high-performance military flying’	34% for HQ group (6 months)
		low-G: 34 ± 7				60% for low-G group (6 months)
		high-G: 30 ± 5				61% for high-G group (6 months)
31	105	20–29: n = 47	Norway	Fighter pilots	‘Neck pain events in general and specifically in the last 12 months’	50% (1 year)
		30–39: n = 45
		> 40: n = 13
21	1,296,881	not specified	USA	Army, Navy, Air Force, Marines	‘…derived from an ICD-9 to ICD-10 pain condition crosswalk’	2.99% (1 year)
32	61	< 30: 34%	Netherlands	Military helicopter cabin crew	‘Neck pain was defined as any pain, including aches and discomfort…’	28% (1 year)
		30–40: 39%
		40–55: 27%
33	113	< 30: 41	Netherlands	Military helicopter pilots	‘Neck pain was defined in the questionnaire as any pain, including aches and discomfort in the previous 12 months’	43% (1 year)
		30–40: 51
		40–55: 21
34	58	< 30: 29%	Netherlands	F-16 pilots	‘Pain was defined as any pain or discomfort’	22% (1 year)
		30–40: 46%
		40–55: 25%
27	373	< 25: 23%	Poland	Army soldiers*	Not specified	21% (1 year)
		25–40: 57%
		> 40: 20%
11	58	20–29: 15	Denmark	F-16 pilots	‘…experienced neck pain during or immediately after flight’	83% (1 year)
		30–39: 40
		> 40: 3
25	272	25.3 ± 6.7	Sweden	Marines	‘Musculoskeletal pain was defined as any self-reported episode of pain within the past 6 months’	19.5% (6 months)
35	90	Not specified	Belgium	F-16 pilots	‘Neck pain was defined as pain in the head and neck region’	18.9% (1 year)

DOB, date of birth; FWA, other fixed-wing aircraft; HPA, high-performance aircraft; HQ, headquarters’ posts; RWA, rotary-wing aircraft.

*Main battle tank (MBT) units of the army.