Table 3.

Results of meta regression of diagnostic criteria, study country, night work and sample size on SWD prevalence.

Predictor	Coefficient	SE	95% CI	Z	2-sided p
Intercept	1.122	0.898	−0.639 to 2.882	1.25	0.212
Diagnostic criteria	−0.914	0.418	−1.733 to −0.096	−2.19	0.027
Study country	0.415	0.322	−0.216 to 1.047	1.29	0.197
Night work	0.192	0.364	−0.906 to 2.882	−0.53	0.597
Sample size	−0.345	0.125	−0.591 to 0.099	−2.75	0.006

Diagnostic criteria (ICSD-2 = 0, ICSD-3 = 1), study country (developed = 0, developing = 1), and night work (includes night work: no = 0, yes = 1). k = 29. R² = 0.