Construct validity and test-retest reliability of a chrononutrition questionnaire for shift work and non-shift work populations

Figures & data

Figure 1. Flow diagram of individuals who underwent screening, enrolment, and completed the study, including exclusion criteria.

Table 1. Data sources and variables included in analyses. A shift worker may perform one or more of: morning shift, afternoon shift, and night shift.

	Sleep			Temporal Patterns of Eating
Population	Context	REDCap Questions	Variables	Context	REDCap Questions	Variables
General Population	Work/school days Work/school-free days	Sleep time Wake time	Sleep time (hh:mm) Wake time (hh:mm) Sleep duration (hh:mm) Mid-sleep time (hh:mm) Chronotype MSFSC (hh:mm)	Work/school days Work/school-free days	Regularity of main meals and snacks Times of all eating occasions including: Main meals Snacks Largest eating occasion(s)	Meal regularity (%) Snack regularity (%) Meal frequency (count/24 h) Snack frequency (count/24 h) Total frequency (count/24 h) Duration of eating window (hh:mm) Time of first eating occasion (hh:mm) Time of last eating occasion (hh:mm) Time of largest eating occasion (based on energy) (hh:mm) Time of main meal 1 Time of main meal 2 Time of main meal 3
Shift-workers	Between two: Morning shifts Afternoon shifts Night shifts Between two work-free days after: Morning shifts Afternoon shifts Night shifts			On the day of: a morning shift an afternoon shift a night shift a split shift a work-free day after a work-free day

Table 2. Demographic details at baseline. *A shift worker may perform one or more of: morning shift, afternoon shift, and night shift. ^#Categories for ethnicity were derived from the Australian standard classification of cultural and ethnic groups 2019 (Statistics 2019). ^{^}Calculated based on data from the CNQ by splitting MSF_SC distribution of the study population in thirds; chronotype could not be calculated for all shift workers as insufficient information was provided about work schedule.

		Total	General Population		Shift workers
Sample size		105	58		47
Age		45.33 ± 16.4 years	47.1 ± 18.5 years		43.1 ± 13.4 years
Body Mass Index (BMI)		27.3 ± 5.6 kg/m^2	26.2 ± 5.5 kg/m^2		28.6 ± 5.4 kg/m^2
Gender	Male	27 (25.7%)	9		18
	Female	78 (74.3%)	49		29
Ethnicity^#	North-West European	72 (68.6%)	36		36
	Southern and Eastern European	9 (8.6%)	6		3
	South-East Asian	7 (6.7%)	5		2
	North-East Asian	5 (4.8%)	4		1
	Southern and Central Asian	8 (7.6%)	5		3
	Peoples of the Americas:	1 (1%)	1		0
	People of the Pacific Islands	2 (1.9%)	1		1
	Aboriginal or Torres Strait Islander	1 (1%)	0		1
Chronotype^^	Morning (<2:45 h)	33	27 (47%)		6 (20%)
	Intermediate (2:45–3:40 h)	26	16 (28%)		10 (33%)
	Evening(≥3:41 h)	29	15 (26%)		14 (47%)
Work commitments			Work	23	Morning shift*	33
			School	4	Afternoon shift*	27
			Work and School	11	Night shift*	36
			Retired/unemployed	20	Split shift	2

Table 3. Sleep variables derived from CNQ compared to sleep diaries for General Population and for shift workers on morning, afternoon, and night shifts, and their following days off. Columns show mean values from the CNQ and Bland-Altman-calculated mean differences (Diff=sleep Diary-CNQ) and the range of the 95% confidence intervals (CI range=CI upper limit – CI lower limit). Bolded values show results of paired samples t-tests comparing CNQ and diary values that were significantly different, p < 0.05. Sample sizes less than 10 are marked with an ^.

				Shift workers
	General Population			Morning shift			Afternoon shift			Night shift
	CNQ	Diff	95%CI Range	CNQ	Diff	95%CI Range	CNQ	Diff	95%CI Range	CNQ	Diff	95%CI Range
Workday
Sleep time	22:32	00:24	−01:15–02:04	22:12	00:02	−01:41–01:45	01:05	−00:05^	−01:53–01:42	08:01	00:12	−02:18–02:44
Wake time	06:28	00:13	−00:50–01:18	05:25	00:10	−01:27–01:48	09:00	−00:43^	−02:45–01:18	14:53	−00:21	−04:15–03:32
Sleep duration	07:55	−00:10	−01:55–1:34	07:12	00:08	−02:03–02:19	07:55	−00:38^	−03:05–01:48	06:52	−00:33	−02:44–01:36
Mid-sleep time	02:30	00:19	−00:46–01:24	01:48	00:06	−01:10–01:23	05:02	−00:24^	−01:52–01:04	11:27	−00:04	−03:10–03:01
Free day
Sleep time	22:55	00:08	−01:23–01:40	23:00	−00:11^	−01:27–01:04	00:00	00:02^	−03:20–03:25	23:06	00:30	−02:24–03:26
Wake time	07:28	−00:08	−01:40–01:24	07:22	00:28^	−01:47–02:44	08:52	−00:38^	−03:00–01:44	08:04	00:24	−02:15–03:05
Sleep duration	08:32	−00:16	−01:56–01:23	08:22	00:40^	−02:40–04:00	08:52	−00:40^	−03:08–01:47	08:58	−00:06	−03:47–03:35
Mid-sleep time	03:12	00:00	−01:17–01:17	03:11	00:08^	−00:36–00:53	04:26	−00:18^	−02:57–02:21	03:35	00:27	−01:38–02:34

Table 4. Temporal patterns of eating variables derived from CNQ compared to food diaries for General Population. Columns show mean values from the CNQ, Bland-Altman-calculated mean differences (Diff = Food Diary-CNQ), and the range of the 95% confidence intervals (95%CI range = CI upper limit – CI lower limit). Bolded values show results of paired samples t-tests comparing CNQ and diary values that were significantly different, p < 0.05. n/a: Bland Altman analyses and 95% CI not calculated for regularity as it was a categorical variable.

		Workday			Free day
		CNQ	Diff	95%CI Range	CNQ	Diff	95%CI Range
Regularity (%)	Meal	75.68	−8.89	n/a	65.63	1.48	n/a
	Snack	44.44	−14.25	n/a	42.05	−14.36	n/a
Frequency (n)	Meal	2.57	0.05	−0.90–1.00	2.72	−0.05	−0.92–0.82
	Snack	2.14	−0.21	−3.07–2.66	1.91	0.21	−2.37–2.79
	Total	4.70	−0.15	−2.91–2.60	4.64	0.15	−2.41–2.72
Duration (hh:mm)	Eating window	11:13	−00:13	−03:26–03:00	10:38	−00:19	−04:40–04:01
Eating Occasions (hh:mm)	First	08:18	00:13	−02:47–03:14	08:49	00:15	−02:50–03:21
	Last	19:32	00:02	−02:25–02:30	19:32	−00:03	−03:48–03:41
	Largest	17:48	-01:30	−06:32–03:32	17:24	-01:34	−07:44–04:35
	Meal 1	09:41	−00:51	−06:15–04:32	08:51	00:00	−02:26–02:25
	Meal 2	15:00	-01:10	−06:28–04:08	14:01	−00:37	−05:42–04:28
	Meal 3	18:47	00:06	−01:05–01:17	18:36	00:05	−00:59–01:09

Table 5. Temporal patterns of eating variables derived from CNQ compared to food diaries for shift workers on morning, afternoon, and night shifts, and days off. Columns show mean values from the CNQ, Bland-Altman-calculated mean differences (Diff = Food Diary-CNQ), and the range of the 95% confidence intervals (95%CI range = CI upper limit – CI lower limit). Bolded values show results of paired samples t-tests comparing CNQ and diary values that were significantly different, p < 0.05. Sample sizes less than 10 are marked with an ^. n/a: Bland Altman analyses and 95% CI not calculated for regularity as it was a categorical variable.

		Morning shift			Afternoon shift			Night shift			Free day
		CNQ	Diff	95%CI Range	CNQ	Diff	95%CI Range	CNQ	Diff	95%CI Range	CNQ	Diff	95%CI Range
Regularity (%)	Meal	55.56	17.72	n/a	52.08	−2.67	n/a	70.65	−22.52	n/a	66.30	−10.57	n/a
	Snack	36.11	−8.33	n/a	37.50	−16.67	n/a	46.74	−17.17	n/a	36.36	−12.55	n/a
Frequency (n)	Meal	2.33	0.24	−1.40–1.87	2.33	−0.28	−1.60–1.04	2.09	0.40	−1.49–2.3	2.74	−0.26	−1.64–1.12
	Snack	2.28	0.74	−2.76–4.24	2.25	−0.37	−2.65–1.92	2.09	0.51	−2.72–3.73	1.74	0.38	−2.87–3.64
	Total	4.61	0.98	−1.97–3.92	4.58	−0.65	−3.26–1.96	4.17	0.73	−2.97–4.43	4.48	0.12	−3.04–3.29
Duration (hh:mm)	Eating Window	12:42	00:00	−05:16–5:16	12:01	-02:15	−08:20–03:50	14:03	02:02	−04:23–08:29	11:08	-01:31	−04:24–01:21
Eating Occasions (hh:mm)	First	07:54	−00:04	−04:55–04:45	10:18	01:34	−04:31–07:40	14:39	−01:37	−10:36–07:21	08:35	01:02	−01:53–03:57
	Last	20:36	−00:05	−04:17–04:07	22:20	−00:40	−04:58–03:37	04:43	00:25	−06:57–07:47	19:44	−00:24	−03:16–02:27
	Largest	18:06	−01:06	−08:48–06:34	16:47	−00:20	−06:57–06:16	19:23	00:33	−10:06–11:13	18:07	-02:31	08:18–03:16
	Meal 1	09:35	00:11	−05:01–05:24	09:47	02:25^	−03:11–08:03	15:11	−02:02	−14:13–10:08	09:20	00:21	−03:18–04:00
	Meal 2	15:36	−00:21	−03:54–03:12	15:36	01:14^	−05:13–07:41	00:00	-05:12	−19:13–08:48	14:39	−00:51	−06:02–04:20
	Meal 3	18:41	−00:03*	−01:35–01:28	19:45	−00:04^	−00:43–00:34	23:12	01:24^	−03:29–06:18	18:32	00:23	−01:11–01:59

Figure 2. (a) Test-retest reliability of sleep variables represented on the left as a box (ICC) and whiskers (upper and lower confidence intervals) plot and on the right as heat map, ranging from dark green (excellent reliability) to red (poor reliability). (b) Convergent validity of sleep variables represented on the left as a box (r_s) and whiskers (upper and lower confidence intervals) plot and on the right as heat map, ranging from dark green (large effect size) to red (small effect size). Sample sizes less than 10 are marked with a ^. GP: general population; SW: shift worker; W: workday.

Figure 3. (a) Test-retest reliability of temporal patterns of eating variables represented on the left as a box (Kappa for regularity and ICC for frequency, duration, and time) and whiskers (upper and lower confidence intervals) plot and on the right as heat map, ranging from dark green (excellent reliability) to red (poor reliability). (b) Convergent validity of temporal patterns of eating variables represented on the left as a box (r_s) and whiskers (upper and lower confidence intervals) plot and on the right as heat map, ranging from dark green (large effect size) to red (small effect size). Sample sizes less than 10 are marked with a ^. GP: general population; SW: shift worker; W: workday; FD: free day; M: morning shift; A: afternoon shift; N: night shift; EW: eating window; EO: eating occasion.

Table

Recommended changes to the CNQ

Shift workers should be asked to specify the pattern of shift types and shift-free days they have within each shift cycle (based on their last shift cycle) in order to have sufficient information to calculate chronotype Temporal patterns of eating on a night shift should be captured within wake time before a night shift and sleep time after a night shift from the 2^nd night shift onwards. Include a 24-h conversion list to support participants in filling in the CNQ.

Statistics ABo. 2019. Australian standard classification of cultural and ethnic groups (ASCCEG). Canberra, Australia: Commonwealth of Australia.

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Data availability statement

The data that support the findings of this study are available from the corresponding author, YYP, upon reasonable request.