Table 3.

Spearman correlation coefficients between the PHQ-8 score and sleep subscore^a on the 3 study sites and their 95% confidence intervals, z score statistics, and P values.

Study site	r	95% CI	z score	P value
KCLb	.74	0.71, 0.76	41.99	<.001
CIBERc	.78	0.75, 0.81	32.09	<.001
VUmcd	.64	0.58, 0.69	18.75	<.001
Total	.73	0.71, 0.74	54.48	<.001

^aSleep subscore represents the score of subitem 3 in the PHQ-8.

^bKCL: King’s College London.

^cCIBER: Centro de Investigación Biomédican en Red.

^dVUmc: Vrije Universiteit Medisch Centrum.