Severely malnourished children with a low weight-for-height have similar mortality to those with a low mid-upper-arm-circumference: II. Systematic literature review and meta-analysis

Table 3 The effect of mathematical coupling on the interpretation of CFR and possibility of Simpson’s paradox

Study	Author & year	Single deficits alone					Single and both deficits					Difference WHZ-MUAC
		S-whz	S-muac	S-whz v S-muac			All-whz	All-muac	All-whz v All-muac			S-whz-S-muac	All-whz-All-muac	Effect on CFR
		CFR	CFR	χ²	Fisher	Cramer	CFR	CFR	χ²	Fisher	Cramer	S-whz-S-muac	All-whz-All-muac	Effect on CFR
		%	%	p	p		%	%	p	p
1	Aguayo 2015	0.23	0.23	nc	(0.96)	0.00	0.58	0.61	0.81	nc	0.00	−0.01	−0.04	>All
2	Grellety 2012	1.69	1.20	nc	0.73	0.02	3.03	2.83	0.88	0.880	0.01	0.50	0.20	>S
3	Grellety 2015	0.87	4.76	nc	(0.19)	0.05	1.79	3.76	0.002	nc	0.06	−3.89	−1.97	>S
4	Isanaka 2015	0.57	0.43	nc	(0.68)	0.01	0.61	0.54	0.77	nc	0.01	0.14	0.08	>S
5	Lowlaavar 2016	6.43	0.00	nc	0.14	0.10	9.13	10.99	0.61	0.607	0.03	6.43	−1.86	Reverse
6	LaCourse 2014	6.90	5.88	nc	0.83	0.02	6.67	5.95	nc	0.860	0.01	1.01	0.71	>S
7	Olofin 2016	15.52	13.25	0.52	0.52	0.03	28.52	19.51	0.002	nc	0.10	2.27	9.01	>All
8	Berkley 2005	10.11	10.94	0.74	0.74	0.01	19.97	19.01	0.63	nc	0.01	−0.83	0.96	Reverse
9	Chiabi 2017	4.35	14.29	nc	0.31	0.17	22.35	25.30	0.65	0.659	0.03	−9.94	−2.95	>S
10	Sachdeva 2016	7.89	20.00	0.004	0.005	0.17	11.83	18.72	0.021	0.023	0.09	−12.11	−6.89	>S

S-whz WHZ below cut off point with MUAC above cut-off point as defined in the paper, S-muac MUAC below cut off point with WHZ above cut-off point as defined in the paper, All-whz WHZ below the cut-off point, with MUAC either above or below the cut-off point as defined in the paper, All-muac MUAC below the cut-off point, WHZ either above or below the cut-off as defined in the paper, S-whz–S-muac (single deficit) WHZ minus MUAC CFR, All-whz – All-muac (combined deficits) WHZ minus MUAC CFR, CFR Case Fatality Rate in percentage; χ² significance of Chi-squared analysis of MUAC against WHZ CFRs; Fisher Fisher’s exact test, two-sided mid P-value (values in parentheses are approximate as one cell number too large); Cramer Cramer’s V of association between variables; “>All” the difference in CFRs between WHZ and MUAC is greater with All-whz/muac; “>S” the difference is greater with S-whz/muac; “Reverse” the direction of the change is reversed (Simpson’s paradox), negative numbers WHZ < MUAC, positive numbers WHZ > MUAC. Significant differences are shown in bold script

ISSN: 1475-2891