Table 4.

Characteristics of studies considered for the primary analysis where 24-h urine volume was presented as median (IQR), n = 7 studies

Study	Study Year(s)	n	Male, n (%)	Valid urine samples	Age range (years)	Age, mean (SD) years	Country	Exclusion criteria for urine samples	NOS score
									Score out of 10	Rating*
Campanozzi [81]	Not described	303	303 (100%)	303	6–9	10.1 (2.9)	Italy	Creatinine excretion < 0.1 mmol/kg/day [81]	6	Medium
		228	228 (100%)	228	9–11.3
		235	235 (100%)	235	11.4–18
		162	0 (0%)	162	6–9
		180	0 (0%)	180	9–11.3
		316	0 (0%)	316	11.4–18
Degen [25]	1985–1989	69	35 (51%)	164	6–10	10.2 (*)	Dortmund, Germany	(1) Creatinine excretion < 0.1 mmol/kg/day (2) Samples reported or found to contain incomplete micturations	6	Medium
	1990–1994	70	35 (50%)	197	11–13	13.0 (*)
Grases [82]	Not described	105	64 (61%)	105	5–17	12.0 (3.0)	Majorca, Spain	Not described	1	Low
Libuda [26]	2003–2009	15	15 (100%)	18	3–3.9	3.1 (*)	Dortmund, Germany	Creatinine excretion < 0.1 mmol/kg/day	5	Medium
		54	54 (100%)	83	13–14.9	14.0 (*)
		66	66 (100%)	145	15–18	16.2 (*)
		24	0 (0%)	25	3–3.9	3.2 (*)
		56	0 (0%)	84	13–14.9	14.0 (*)
		70	0 (0%)	144	15–18	16.2 (*)
Montenegro-Bethancourt [28]	2000–2010	146	146 (100%)	269	4–6.9	5.0 (*)	Dortmund, Germany	(1) Creatinine excretion < 0.1 mmol/kg/day (2) Collection time < 20 h	5	Medium
		147	0 (0%)	264	4–6.9	5.0 (*)
Montenegro-Bethancourt [29]	1996–2002	30	30 (100%)	30	13–18	15.0 (*)	Dortmund, Germany	(1) Creatinine excretion < 0.1 mmol/kg/day (2) No reported missed collections	6	Medium
		30	0 (0%)	30	13–18	14.0 (*)
Montenegro-Bethancourt [30]	1993–2010	265	265(100%)	985	6–13	9.0 (*)	Dortmund, Germany	Creatinine excretion < 0.1 mmol/kg/day	6	Medium
		251	0 (0%)	974	6–13	9.0 (*)

NOS Newcastle-Ottawa Scale for cohort studies

*NOS rating based on score out of 10—low: 0–3; medium: 4–7; high 8–10