Preliminary assessment of rotating shiftwork risk in a 24-hours metal industry

Abstract

BACKGROUND:

Rotational shiftwork (RS) has been linked to increased risk for safety and health of shift workers, globally. A growing literature has revealed a trend toward increased accident and injury rates in shift workers than non-shift workers.

AIMS:

The present research was aimed: 1) to develop a methodological path for a preliminary objective assessment of occupational risk by RS in a metal industry 2) to detect the consequent effective interventions for moderating the RS risk.

METHODS:

A modified version of the Rotational Shiftwork Questionnaire was designed by a panel of experts, through a Delphi study; the questionnaire was used for a pilot study to assess the RS risk in a metal industry.

RESULTS:

The questionnaire was entitled Rotating Shiftwork Questionnaire-Industry (RSQ-I) and was made up of two sections: 1) Sentinel Events; 2) Risk Factors. The assessment of RS risk showed a medium level of risk in the studied metal industry. Organizational level interventions were detected for moderating the impact of RS-risk on workers’ safety and health.

CONCLUSION:

RSQ-I showed a valid and reliable tool to analyze RS risk in a 24-hours metal industry. The pilot study demonstrated the effectiveness and feasibility of the introduced RSQ-I to approach the risk, through the analysis of both sentinel events and shift schedules.

Keywords

Shift schedules circadian rhythm questionnaire occupational health risk assessment

1 Introduction

The assessment of occupational risk by rotational shift work including night shift (RS) represents a challenge for occupational health professionals; in fact, schedules being used may vary due to organizational factors such as direction of rotation (i.e. clockwise or counter-clockwise), starting and finishing times, amount of night shifts and rest days between the shifts [1 –5]. A growing literature has revealed that shift workers more frequently incur increased accident and injury rates than non-shift workers [6 –8]; in addition, shift work has been linked to poor diet, insufficient physical activity, occupational stress, burnout, sleeping difficulties, reduced work efficiency, decreased job satisfaction, increased rates of absenteeism and turnover [9 –12]. In a recent meta-analysis, Torquati et al. [13] found that shift-workers reported increased risk of cardiovascular diseases morbidity (17%) and mortality (20%), compared to non-shift-workers, and showed increased risk of cardiovascular diseases after five years of shift work. These findings are in line with the study of Brown et al. [14] that found an increased risk for ischemic strokes in shift workers and observed a linear trend between the number of years of rotating shift work and ischemic stroke risk, with a 4% increase in ischemic stroke risk for each 5 years of shift work. Many authors demonstrated the relationship between RS and obesity [15], and supported the growing evidence that night shift work is a risk factor for disruption in homeostasis, leading to metabolic disorders [16]; moreover, shift workers have been reported more frequently physically inactive than non-shift workers, despite the evidence that regular physical activity is associated to health benefits, including the maintaining of healthy body mass index; in particular, several studies highlighted the relationship between circadian rhythm disruption and less physical activity in shift workers than their non-shift working counterpart [2 , 18], and suggested physical activity interventions as effective to better the health status in shift workers [19, 20]. The circadian rhythm disruption due to shift work has been also linked to deregulation of circadian clock genes [21] and to breast cancer in women, and in 2010 the International Agency for Research on Cancer (IARC) classified the “shiftwork that involves circadian disruption” as “probably carcinogenic to humans” (Group 2A carcinogen) [1]. IARC based their conclusion on studies on long-term night female workers who have shown a higher risk of breast cancer than women who do not work at night. According to IARC monograph, rotating shift workers are defined people alternating more or less periodically on different shifts.

In a recent study, we developed the Rotating Shiftwork Questionnaire (RSQ) to assess, in a preliminary step, the rotational shift work risk in the hospital wards [22]. Considering the relevance of this topic also in working sectors different from healthcare, in the present study we developed a methodological path for a preliminary objective assessment of rotational shift work risk in a metal industry, based on a modified version of the RSQ.

2 Methods

According to the methodology adopted to design the RSQ [22], in this study the definition of RS is addressed to continuous shift work, running 24 hours per day, 7 days per week, with weekends. This definition does not include fixed shifts like straight nights, straight afternoons or straight days and, generally, fixed shifts are not included here. The first step of the research consisted in a Delphi study aimed to design a questionnaire for assessing the rotating shift work risk in metal workers. In the second step, the questionnaire was implemented in a metal industry with the aims: 1) to detect, preliminarily and objectively, the occupational risk profile for homogeneous groups exposed to RS and 2) to detect the consequent interventions effective in minimizing this risk.

In phase I of this study, the authors designed the Rotating Shiftwork Questionnaire-Industry (RSQ-I) with the aim to calculate the objective RS-Risk (RSR) index, empirically defined as the product of the interaction between sentinel events (SE) and risk factors (RF) associated with RS (RSR = SExRF); RSQ-I was based on RSQ for healthcare sector [22] and was designed after a review of literature to collect recent findings regarding sentinel events (SE) and risk factors (RF) addressed to RS schedules [23 –31]. The questionnaire was addressed to homogeneous groups of workers exposed to RS and did not analyze the individual characteristics of exposed workers (i.e. demographics, biological responses). In order to obtain consensus on the RSQ-I, the Delphi method was used [32].∥In phase II of this study, for the validation of RSQ-I a panel of eligible experts was selected in Italy; the experts were identified based on specific criteria, including having active involvement in occupational risk assessment, being trainers on safety and health at work, having prior publications in the field of shiftwork.∥Each expert was asked to rate the steps on a Likert scale from 1 “not important” to 5 “essential”; means and 95% confidence intervals (CI) were calculated for each step to identify relevant steps. The 95% CI were used to quantify the variability of the experts’ responses. Rated on a Likert scale 1–5, the CI were between 1.00 and 5.00. An item was accepted as a key item if the lower confidence limit was ≥3.00. A step was excluded if the upper confidence limit was ≤3.50.∥In Delphi round 2, a cut off point for consensus was predetermined. Consensus was established when at least 80% of the respondents rated the step as ≥3. This step was then accepted as a key step. If the 80% threshold was not reached, the step was excluded.∥A Cronbach’s alpha was used as a measure of consistency among the opinions of the experts, and a value of ≥0.80 was chosen as a cut-off value for determining consensus.∥In phase III of the present study the questionnaire validated by the panelists was used in a pilot study, performed in the period between April and May 2018, to assess the RS risk in a 24-hours working industry, in Salento (Italy), in which were employed 70 metal workers (Table 1); the questionnaire was administered to the chief human resources officer of such industry, with the aim to assess the feasibility of RSQ.

Table 1
Sample demographics

Workers N.

Entire group 70

Females 29

Males 41

Age range (years) Females N (%) Males N (%)

<35 7 (24.1) 9 (22.0)

36–45 12 (41.5) 15 (36.5)

46–55 7 (24.1) 10 (24.4)

56–65 3 (10.3) 5 (12.2)

>65 0 (0.0) 2 (4.9)

Years of shiftwork Females N (%) Males N (%)

<5 5 (17.2) 8 (19.6)

5–10 7 (24.2) 11 (26.8)

11–20 11 (37.9) 14 (34.1)

21–30 4 (13.8) 5 (12.2)

>30 2 (6.9) 3 (7.3)

Workers	N.
Entire group	70
Females	29
Males	41
Age range (years)	Females N (%)	Males N (%)
<35	7 (24.1)	9 (22.0)
36–45	12 (41.5)	15 (36.5)
46–55	7 (24.1)	10 (24.4)
56–65	3 (10.3)	5 (12.2)
>65	0 (0.0)	2 (4.9)
Years of shiftwork	Females N (%)	Males N (%)
<5	5 (17.2)	8 (19.6)
5–10	7 (24.2)	11 (26.8)
11–20	11 (37.9)	14 (34.1)
21–30	4 (13.8)	5 (12.2)
>30	2 (6.9)	3 (7.3)

The study was performed as part of the obligatory evaluation of occupational risks, which is required by Italian Legislative Decree 81/08. This study required no formal approval by the local ethics committee.

3 Results

Fifteen experts were invited to participate; of these, 10 (66,7%) agreed and completed the first and second round (6 Occupational physicians, 2 Clinical Psychologists, 2 Occupational safety professionals); Cronbach’s alpha was calculated and resulted 0.90 and showed high internal consistency among the panelists for the items included in the final questionnaire. The results are presented in Tables 2 –4. The Delphi round 1 had 23 items to be rated; 21 items reached the consensus (Table 2), the remaining 2 items were reassessed in round 2 and were included because they reached consensus (Table 3). The final RSQ-I is made up of 23 items (Table 4); the section SE identifies seven indicators of RS-related problems (i.e. work-related injuries, health impairments arising from fatigue and the mismatch of circadian rhythm with the work, impaired work performance, overworking etc.) and identifies three areas of risk: low (a score of 0 and 7), medium (a score of 8 and 13), and high (a score >14). Low, medium and high risk scores are converted respectively into 1, 1.5, 2. The section RF identifies 14 organizational factors of RS risk (RF).

Table 2
Delphi round I: Rotating Shiftwork Questionnaire-Industry (RSQ-I) for a 24-hours metal industry

2.1 Sentinel events (SE) ():

Decreased (score = 0) Unchanged (score = 1) Increased (score = 2) IC 95%

1) Work-related injuries () 0 1 2 4,12–4,88

2) Mistakes at work () 0 1 2 2,57–3,63 Reassessed in round 2

3) Lack of progress towards strategic goals (in regard to the industrial strategic plan) () 0 1 2 2,51–3,48 Reassessed in round 2

4) Sick leave () 0 1 2 3,54–4,61

5) Unused vacations () 0 1 2 3,75–4,65

6) Over working time () 0 1 2 4,03–4,77

7) Staff turnover () (No. of employees leaving/total No. of Employees) 0 1 2 3,82–4,78

8) Requests for extra medical checks related to RS risk () 0 1 2 4,12–4,88

9) Work-related stress notifications () 0 1 2 3,96–4,64

Table for converting SE scores and detecting areas of risk.

SCORE 0–7 8–13 14–18 IC 95%

SCORE CONVERSION 1,00 1,50 2,00 3,82–4,78

AREA OF RISK LOW MEDIUM HIGH 5,00–5,00

2.2 Risk Factors (RF): Organizational factors of Rotating Shiftwork risk ():

Good (-) Ok (–) Critical (—) Problematical (—-) IC 95%

1) Regularity of shift cycles 0 1 2 3 4,12–4,88

2) Forward-rotating schedules (Morning-Afternoon-Night) 0 1 2 3 4,03–4,77

3) Morning starts after 7.00 a.m. 0 1 2 3 3,41–4,6

4) Working not alone in a shift 0 1 2 3 4,23–4,97

5) Predictability of the shift 0 1 2 3 3,57–4,63

6) Shift Flexibility 0 1 2 3 3,90–4,90

7) Rest periods between consecutive shifts (>11 hours) 0 1 2 3 3,47–4,73

8) Rest day after night shift 0 1 2 3 3,82–4,78

9) A short break of 5–15 minutes within the shift 0 1 2 3 4,12–4,88

10) Speed of shift rotation (number of consecutive days worked before changing shift) Speed (every 1-2-or 3 days) Very slow (every 21 or plus days) Slow (15 or 20 days) Intermediate (every 4 or 14 days)

Score 0 1 2 3 3,71–4,89

11) Shift duration <8 hours 8–12 hours 12–18 hours >18 hours

0 1 2 3 3,69–4,51

12) Nights per month (no.) 1–3 4–5 6–7 >7

Score 0 1 2 3 3,75–4,65

13) Consecutive nights per week 0 1 2 >2

Score 0 1 2 3 4,23–4,97

14) Free week-ends per month (no.) ≥3 2 1 0

Score 0 1 2 3 4,03–4,77

2.1 Sentinel events (SE) (*):
	Decreased (score = 0)	Unchanged (score = 1)	Increased (score = 2)	IC 95%
1) Work-related injuries (**)	0	1	2	4,12–4,88
2) Mistakes at work (**)	0	1	2	2,57–3,63 Reassessed in round 2
3) Lack of progress towards strategic goals (in regard to the industrial strategic plan) (**)	0	1	2	2,51–3,48 Reassessed in round 2
4) Sick leave (**)	0	1	2	3,54–4,61
5) Unused vacations (**)	0	1	2	3,75–4,65
6) Over working time (**)	0	1	2	4,03–4,77
7) Staff turnover (**) (No. of employees leaving/total No. of Employees)	0	1	2	3,82–4,78
8) Requests for extra medical checks related to RS risk (**)	0	1	2	4,12–4,88
9) Work-related stress notifications (**)	0	1	2	3,96–4,64
Table for converting SE scores and detecting areas of risk.
SCORE	0–7	8–13	14–18	IC 95%
SCORE CONVERSION	1,00	1,50	2,00	3,82–4,78
AREA OF RISK	LOW	MEDIUM	HIGH	5,00–5,00
2.2 Risk Factors (RF): Organizational factors of Rotating Shiftwork risk (***):
	Good (-)	Ok (–)	Critical (—)	Problematical (—-)	IC 95%
1) Regularity of shift cycles	0	1	2	3	4,12–4,88
2) Forward-rotating schedules (Morning-Afternoon-Night)	0	1	2	3	4,03–4,77
3) Morning starts after 7.00 a.m.	0	1	2	3	3,41–4,6
4) Working not alone in a shift	0	1	2	3	4,23–4,97
5) Predictability of the shift	0	1	2	3	3,57–4,63
6) Shift Flexibility	0	1	2	3	3,90–4,90
7) Rest periods between consecutive shifts (>11 hours)	0	1	2	3	3,47–4,73
8) Rest day after night shift	0	1	2	3	3,82–4,78
9) A short break of 5–15 minutes within the shift	0	1	2	3	4,12–4,88
10) Speed of shift rotation (number of consecutive days worked before changing shift)	Speed (every 1-2-or 3 days)	Very slow (every 21 or plus days)	Slow (15 or 20 days)	Intermediate (every 4 or 14 days)
Score	0	1	2	3	3,71–4,89
11) Shift duration	<8 hours	8–12 hours	12–18 hours	>18 hours
0	1	2	3	3,69–4,51
12) Nights per month (no.)	1–3	4–5	6–7	>7
Score	0	1	2	3	3,75–4,65
13) Consecutive nights per week	0	1	2	>2
Score	0	1	2	3	4,23–4,97
14) Free week-ends per month (no.)	≥3	2	1	0
Score	0	1	2	3	4,03–4,77

(*) Comparison between the current biennium and the previous; (**) if not detected = 0; (***) data of the current biennium; - if detected in 95–100% of the shifts = 0; - - if detected in 75–94% of the shifts = 1; — if detected in 50 –74% of the shifts = 2; —- if detected in < 50% of the shifts = 3.

Rotating Shiftwork Risk Index (RSR) = SE×RF
LOW	MEDIUM	HIGH	IC 95%
≤14	14,1–26	>26	5,00–5,00
Actions
Monitoring plan	Corrective measures and new assessment two years later	Corrective measures, eventually in-depth evaluation (*) and new assessment two years later	4,23–4,97

(*) This phase aims to gather important information on the organization’s “health” through assessment of employees’ perceptions. It is required if corrective measures prove inadequate. However, organizations may also use it to collect further in-depth information.

Table 3

Delphi round II: reassessed items for RSQ-I

Sentinel events	Likert score 1-2 (%)	Likert score 3–5 (%)
Mistakes at works	20	80
Lack of progress towards strategic goals (in regard to the industrial strategic plan)	20	80

Accepted as item: “Mistakes at work” and “Lack of progress towards strategic goals (in regard to the industrial strategic plan)”.

Table 4

Rotating Shiftwork Questionnaire-Industry (RSQ-I) for a 24-hours metal industry: final instrument

4.1 Sentinel events (SE) (*):
	Decreased (score = 0)	Unchanged (score = 1)	Increased (score = 2)
1) Work-related injuries (**)	0	1	2
2) Sick leave (**)	0	1	2
3) Unused vacations (**)	0	1	2
4) Over working time (**)	0	1	2
5) Staff turnover (**) (No. of employees leaving/total No. of Employees)	0	1	2
6) Requests for extra medical checks related to RS risk (**)	0	1	2
7) Work-related stress notifications (**)	0	1	2
8) Mistakes at work (**)	0	1	2
9) Lack of progress towards strategic goals (in regard to the industrial strategic plan) (**)	0	1	2
Conversion of SE scores and detection of areas of risk.
SCORE	0 –7	8 –13	14–18
SCORE CONVERSION	1,00	1,50	2,00
AREA OF RISK	LOW	MEDIUM	HIGH
4.2 Risk Factors (RF): Organizational factors of Rotating Shiftwork risk (***):
	Good (-)	Ok (–)	Critical (—)	Problematical (—-)
1) Regularity of shift cycles	0	1	2	3
2) Forward-rotating schedules (Morning-Afternoon-Night)	0	1	2	3
3) Morning starts after 7.00 a.m.	0	1	2	3
4) Working not alone in a shift	0	1	2	3
5) Predictability of the shift	0	1	2	3
6) Shift Flexibility	0	1	2	3
7) Rest periods between consecutive shifts (>11 hours)	0	1	2	3
8) Rest day after night shift	0	1	2	3
9) A short break of 5–15 minutes within the shift	0	1	2	3
10)Speed of shift rotation (number of consecutive days worked before changing shift)	Speed (every 1-2-or 3 days)	Very slow (every 21 or plus days)	Slow (15 or 20 days)	Intermediate (every 4 or 14 days)
Score	0	1	2	3
11) Shift duration	<8 hours	8–12 hours	12,1–18 hours	>18 hours
0	1	2	3
12) Nights per month (no. per worker)	1–3	3,1–5	5,1–7	>7
Score	0	1	2	3
13) Consecutive nights (no. per week per worker)	0	0,1–1	1,1–2	>2
Score	0	1	2	3
14) Free week-ends per month (no. per worker)	>2	1,1–2	0,1–1	0
Score	0	1	2	3

Rotating Shiftwork Risk Index (RSR) = SE×RF
LOW	MEDIUM	HIGH
≤14	14,1–26	>26
Actions
Monitoring plan	Corrective measures and new assessment two years later	Corrective measures, eventually in-depth evaluation (*) and new assessment two years later

The questionnaire identifies three levels of RSR: low (a score of 0 and 14), medium (a score >14 and ≤26), and high (a score >26).∥The assessment of RSR in the detected 24-hours metal industry, obtained by an objective approach and utilizing the RSQ-I, showed a medium level of RSR among metal workers (score = 18). In particular, the SE section evidenced a low risk (score 5, converted into 1) and the RF section showed a score of 18. The analysis identified the objective RF associated with RS-risk and led to suggest organizational interventions for reducing the sources of RSR among the metal workers, and for prioritizing the interventions targeted on the issues detected by the RSQ-I (Table 5).

Table 5

Problematical issues related to RS-risk among metal workers. Improvement interventions

Problematical issue	Intervention
Shift flexibility	Worker’s participation to the whole process of designing and implementing the shift schedules
Predictability of shift work	Organizational model in wich the shift schedules were designed with thirty days in advance
Forward-rotating schedules (Morning - Afternoon - Night)	Systematic adoption of the forward-rotating schedules
Low workers’ awareness of rotating shiftwork risk	Safety training focused on rotating shiftwork risk

4 Discussion

According to the criteria of RSQ [22] and using a Delphi methodology, the authors achieved consensus among experts in RS risk and a valid, structured and reliable questionnaire was developed. The investigation conducted in a 24-hours metal industry, using the RSQ-I, showed a medium level of RSR among metal workers, susceptible to be minimized through organizational level interventions. In particular, the authors found that RSR was related to: 1) lack in regularity and predictability of shift work; 2) low number of free weekends; 3) direction of the shiftwork; 4) low workers’ awareness of rotating shift work risk. To ensure the predictability of shift work, the authors suggested an organizational model in which the shift schedules were designed with thirty days in advance, ensuring the regularity of shift work model. The authors also suggested to improve the flexibility of shift work schedules through the workers’ participation in the whole process of designing and implementing the shift schedules. The goal of this intervention was to ensure the adaptability of the shift schedules to the needs of each worker, in accordance with the organizational needs of the industry. The number of free week-ends resulted unchangeable because of the shortage of workers employed in the studied Industry. With regard to the direction of the shift work schedules, according to HSE recommendations [24], the authors suggested the systematic adoption of the forward-rotating schedules as more effective to protect workers’ health rather than a backward-rotating schedule (shift rotation in the counterclockwise direction), or other rotating schedules. To improve the workers’ awareness of RSR, the authors suggested safety training programs focused on RSR with the aim to assist RS workers in adopting effective safety strategies to manage and minimize the impact of occupational risks, including RSR, on health and wellness.

RSQ-I showed a valid and reliable tool to analyze RSR in 24-hours working metal industry; the pilot study demonstrated the effectiveness and feasibility of the introduced RSQ-I in approaching the RSR, through the analysis of quantitative data involving indicators (SE, RF) of RSR; the findings were also useful to prioritize and to implement strategic interventions aimed to moderate the risk associated with RS.

Further studies will be necessary to verify the effectiveness of the proposed RSQ-I in the preliminary assessment of RSR among metal workers employed in twenty-four hours industrial wards. To ensure its applicability, the method should actively involve the company occupational safety and health professionals together to chief human resources officer.

5 Limitations

There were several limitations in this study. Firstly, the proposed questionnaire (RSQ-I) analyzed only the objective risk factors related to RS and did not consider the subjective workers’ perception of RS risk. Secondly, the preliminary assessment of RS-risk is addressed to homogeneous groups of HCWs and not to each worker. Thirdly, the analysis of SE was conducted through the comparison of two biennium, and the analysis of RF involved only one biennium, which might influence the precision of the findings.

6 Key points

The Rotating Shift work Questionnaire-Industry (RSQ-I) was designed to assess the objective occupational risk by rotational shift work in a metal industry.

The RSQ-I showed a reliable and effective tool to assess the risk and to detect improvement interventions.

Organizational level interventions targeting shift schedules showed effective for minimizing the risk by rotational shift work.

Conflict of interest

None to report.

Ethical approval

The study was performed as part of the obligatory evaluation of work related stress, required by Italian Legislative Decree 81/08, and needed no formal approval by the local ethics committee.

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