Table 3 Compressed Working Week – retrospective studies (grouped by study design)
StudyDesign and critical appraisal (see criteria in box 3)Setting and participantsSummary results
↑  =  improvement ↓  =  worsening ↔  =  little change
Retrospective cohort studies with control group
Venne, 1993; 199769 70Historical data: 12-month pre-average, 24-month post-averageFinal sample: n = 102 (70 intervention, 32 control)Critical appraisal: 4 5 7 9 10Prison, CanadaPrison guardsFive eight-hour shifts, two days off to two/three 12-hour shifts, two/three days offAbsence↔
Yamada et al, 200171Historical data: 2-, 8-, 14- and 24-month follow-upsFinal sample: n = 205 (189 intervention, 16 control)Critical appraisal:2 4 5 6 9Electronic parts manufacturer, JapanProcessing machine operatorsFive eight-hour shifts, two days off to two/three 12-hour shifts, two/three days offLower back painStiff shoulderJoint painLimb painDimmed sightSore throatPoor sleepDiminished alertnessTirednessIrritationHead heavinessBMIWeightBlood pressure↔↔↔↔↔↔↔↔↔↔↔↔↔↔
Retrospective cohort studies
Laundry & Lees, 1989; 199172 73Historical data: 120-month pre-average, 120-month post-averageFinal sample: n = 247Critical appraisal: 2 4 5 7 8 9 10Synthetic yarn factory, CanadaFactory workers, 85% maleFive eight-hour shifts, two days off to 12-hour shiftsMorbidity (male)Morbidity (female)HeadachesGastric upsetDiarrhoeaAlcohol problemsGeneral malaiseNervous conditionsMinor injury rateSevere injury rateInjury rate (male)Injury rate (female)↑↔↑↑↑↑↔↔↑↔↑↔
Conrad-Beetschart, 199074After only recall data: one-month postFinal sample: n = 78Critical appraisal: 2 4 7 9Oil refinery, SwitzerlandOperators, mainly maleFive eight-hour shifts, two days off to two/three 12-hour shifts, two/three days offSleepHealthLeisure timeTime with partner↑↔↑↑
Pollock et al, 199475Historical data: 18-month pre-average, 18-month post-averagePetrochemical manufacturer and fertiliser manufacturer, AustraliaInjury rates↔
Final sample: n = 300Manufacturing workers.
Critical appraisal: 2 4 5 9Five eight-hour shifts, two days off to four 12-hour shifts, four/six days off
Barter-Trenholm, 199776After only recall dataFinal sample: n = 218Critical appraisal: 2 4 7 9 10Police Force, CanadaPolice officersFive eight-hour shifts, one in three weekends off to 12-hour shifts, one in two weekends offSleep patternsTirednessEffectiveness↔↔↔
Vega & Gilbert, 199777After only recall data: eight-month postHistorical data: 12-month pre-average, 12-month post-averageFinal sample: 34Critical appraisal: 2 7 9 10County Sheriff’s Department, USAPatrol officers, majority male and whiteFive eight-hour shifts, two days off to three 13.3-hour shifts, four days offFatigueQuality of professional livesQuality of personal livesFamily and personal activitiesProductivity↔↑↑↑↑
Richbell et al, 1998*78After only recall dataHistorical data: 12-month pre-average, 12-month post-averageFinal sample: n = 90Critical appraisal: 2 9Police force, UKPolice officersFive eight-hour shifts to Ottawa system (9/10-hour days 10-hour nights).HealthAbsenceQuality of lifeMoraleService↑↑↑↑↑
Wootten, 2000a, 2000b79 80Historical data: three-month pre-average, three-month post-averageFinal sample: n = 20Critical appraisal: 2 4 5 9Hospital, UKNurses7.5-hour to 12-hour shiftsAbsenceAccidentsStaffing costsErrors↓↑↑↑
Baker et al, 200081Historical data: nine-month pre-average, 12- and 24-month post-averagesFinal sample: not statedCritical appraisal: 2 4 5 7 10Coal Mine, AustraliaMiners, maintenance workers, preparation plant workersEight-hour shifts to A: four 12-hour shifts, two/six days off; then from A to B: as system A with addition of three consecutive night shifts and no cap on overtimeAbsenceInjury incident rate↓↑
Bloodworth et al, 200182After only recall dataHistorical data: two-month pre-average, two-month post-averageFinal sample: 16Critical appraisal: 2 4Hospital, UKNurses, all femaleFive 7.5-hour shifts, two days off to two 6.25-hour shifts, two 12-hour shifts, three days offTirednessAbsenceChild carePerformanceStaff costsErrors and incidents↔↑↑↔↑↔
Retrospective repeat cross-section studies
Brinton, 198383Historical data: five-month pre-average, five-month post-averageFinal sample: 76Critical appraisal: 2 4 5 9Paper Mill, USAWood yard workers, all maleFive eight-hour shifts, two days off to four 12-hour shifts, three/four days offInjury frequency rateAbsence↑↑

  • Effect sizes have been added to the text where appropriate and the detailed results are available in online table E3.

  • *This study also used qualitative focus groups.