Table 1 Selected studies: summary of studies in order of level of evidence, with extracted data

Wang et al. 2008[17]

USA

RCT

293 (subset of operators with Rempel 2007 with lower p) Group n= (111;84;98)

Sewing machine operators with back /hip pain

Gp 1: control

Pre and post monthly for 4/12: Pain symptoms- intensity (1-5) and frequency

Mean pain Improv’t gp 2 vs 1: 0.25(95%CI: 0.16, 0.34);GP3 vs 1: 0.43 (0.34-0.51) per month.

Adjustable, swivelling chairs offer advantage (reduction in LB/Hip pain) for workers in seated/UL occupations; flat pan superior to curved?

Obtain means and sd for pain scores for each group (presented graphically in Fig 5A) at 4/12f/u

Gp2: curved pan chair

Gp 3: flat seat pan chair (all received misc items, chairs hgt adjustable)

Remple et al. 2008[19]

USA

RCT

277 (subset with upper p) Group n pain (105;72;100)

Sewing machine operators with neck/ shoulder pain

Gp 1: control Gp2: curved pan chair Gp 3: flat seat pan chair (all received miscel items; intervention chairs hgt adjustable)

Pre and post monthly for 4/12: Pain symptoms- intensity (1-5) and frequency

Mean pain Improv’t gp 2 vs 1: 0.34 (95% CI: 0.28, 0.41); GP3 vs 1: 0.14 (.07-.022) per month.

Adjustable, swivelling chairs offer advantage (reduction in Cx/shoulder pain) for workers in seated/ UL occupations; curved pan superior to flat?

Obtain means and sd for pain scores for each group (presented graphically in Fig 5A) at 4/12f/u

Amick et al. 2003[4]

USA

RCT (assigned according to office location)

192(87;52;S3)

Office workers (>4hrs per day at computer;>6 hrs per day sitting)

Gp1: adjustable chair + training

Pre (2xmonthly) and post intervention (3x over 1 year). Musculo- skeletal symptoms-1. Growth over workday 2. Average pain over workday

Symptom growth over workday: Gp 1<gp2/3 at 12/12f/u (p=0.012). Ave pain levels: Reduced for both Gp 1+2 compared to Gp3

Highly adjustable chairs plus training resulted in less end of day pain and reduced average pain (largest reduction in neck/shoulder, followed by upper and lower back)

Cant separate chair as sole intervention but clear that chair + info is superior to info alone or nothing.

Gp2: training only

Gp3: no intervention

Herbert et al. 2001 [20

USA

Pre and post test

36

Garment workers (“spooling” task), female

Adjustable chairs and training in their use

MS symptom survey prior to and 6/12 after introduction. Joint position in sitting via video (subgroup only). Upper limbs only.

Baseline pain report89% of group; post 63.9% (p=0.007); Reduction in severity at 10/11 anatomic sites after intervention. Only modest declines in awkward posture (small n)

Reduction in people with pain and reduction in severity overall at upper limb anatomical sites. Inconclusive posture change findings.

Gadge et al. 2007[18]

Australia

Sungle case, multiple baseline (ABAB)

4

University students (sitting “most of the time”)

Standard office chair (adjustable) vs “saddle” seat

(dis) Comfort (VAS); Production (typing task speed and accuracy); Posture (videotape) Multiple measures across 4 phases.

Discomfort in lower back increased over time in both chairs but less so in the saddle; discomfort was significantly worse in lower limbs in saddle chair; Productivity no change; Greater trunk to thigh angles in saddle.

Some benefits for lower back discomfort and posture in saddle but also issues (lower limb discomfort).