Importance of reporting quality: An assessment of the COVID-19 meta-analysis laboratory hematology literature

Table 1 Articles considered in the analysis

Ref.	Country1	No. of patients	Evaluated hematologic parameters
Published studies
Borges et al[11]	Multinational, predominantly China	59254	WBC, ANC, ALC, PLT, D-Dimer
Cao et al[12]	China	46959	WBC, ALC
Fu et al[13]	Not stated, likely all China	3600	WBC, ALC, PLT, D-dimer
Henry et al[14]	China, Singapore	2984	WBC, ANC, ALC, MONO, EOS, HGB, PT, PTT, D-dimer
Lagunes-Rangel[15]	China	828	Estimate of N/L ratio
Li et al[16]	China	1995	WBC
Lippi et al[17]	China, Singapore	1099	PLT
Rodriguez-Morales et al[18]	China, Australia	2874	WBC, ALC, HGB
Zhu et al[19]	China	3062	WBC, ALC, D-dimer
Preprint studies
Arabi et al[20]	China	50	WBC
Ebrahami et al[21]	China	2217	WBC, ANC, ALC, HGB, PLT, PT, PTT, D-Dimer
Han et al[22]	China	1208	ALC, ANC, PLT, PT, PTT, D-Dimer
Heydari et al[23]	China, S. Korea	49504	WBC, ANC, ALC, D-dimer
Ma et al[24]	China	53000	ALC, PLT, D-dimer
Nasiri et al[25]	China, Germany	4679	WBC, ANC, ALC, HGB, PLT
Pormohammad et al[26]	China	52251	WBC, ALC, ANC, PLT, HGB
Xu et al[27]	China	4062	WBC, ANC,ALC, PLT, D-dimer
Zhang et al[28]	Not stated, likely all China	275	WBC, ALC

¹Country of origin of patient population. WBC: White blood cell count; ANC: Absolute neutrophil count; ALC: Absolute lymphocyte count; PLT: Platelet count; MONO: Absolute monocyte count; EOS: Absolute eosinophil count; HGB: Hemoglobin; PT: Prothrombin time; PTT: Partial thromboplastin time; N/L: Neutrophil-to-lymphocyte.

Table 2 Institutes of Medicine recommended standards for meta-analysis

Required element	Papers meeting this standard (total number and percentage)	Published/ accepted papers meeting this standard (total number and percentage)	Preprint papers meeting this standard (total number and percentage)
Explain why a pooled estimate might be useful to decision makers	9/19 (47%)	5/9 (56%)	4/10 (40%)
Use expert methodologists to develop, execute, and peer review the meta-analyses	15/19 (79%)	7/9 (78%)	8/10 (80%)
Address heterogeneity among study effects	18/19 (95%)	8/9 (89%)	10/10 (100%)
Accompany all estimates with measures of statistical uncertainty	19/19 (100%)	9/9 (100%)	10/10 (100%)
Assess the sensitivity of conclusions to changes in the protocol, assumptions, and study selection (sensitivity analysis)	12/19 (63%)	5/9 (56%)	7/10 (70%)

Table 3 Preferred Reporting Items for Systemic Reviews and Meta-analyses checklist

Item number	Element	Papers meeting this standard (total number and percentage)	Published/ accepted papers meeting this standard (total number and percentage)	Preprint papers meeting this standard (total number and percentage)
1	Title	19/19 (100%)	8/9 (89%)	10/10 (100%)
2	Structured summary	18/19 (95%)	8/9 (89%)	10/10 (100%)
Introduction
3	Rationale	16/19 (84%)	8/9 (80%)	8/10 (89%)
4	Objectives	17/19 (89%)	9/9 (90%)	8/10 (89%)
Methods
5	Protocol/Registration	16/19 (84%)	8/9 (89%)	8/10 (78%)
6	Eligibility criteria	17/19 (89%)	8/9 (89%)	9/10 (89%)
7	Information sources	18/19 (95%)	9/9 (100%)	9/10 (89%)
8	Search	18/19 (95%)	9/9 (100%)	9/10 (89%)
9	Study selection	19/19 (100%)	9/9 (100%)	10/10 (100%)
10	Data collection process	18/19 (95%)	8/9 (89%)	10/10 (100%)
11	Data items	17/19 (89%)	8/9 (89%)	9/10 (89%)
12	Risk of bias in individual studies	10/19 (53%)	4/9 (44%)	6/10 (56%)
13	Summary measures	15/19 (79%)	6/9 (66%)	8/10 (78%)
14	Synthesis of results	16/19 (84%)	7/9 (78%)	9/10 (89%)
15	Risk of bias across studies	2/19 (11%)	2/9 (22%)	0/10 (0)
16	Additional analyses	2/19 (11%)	1/9 (11%)	1/10 (10%)
Results
17	Study selection	19/19 (100%)	9/9 (100%)	10/10 (100%)
18	Study characteristics	19/19 (100%)	9/9 (100%)	10/10 (100%)
19	Risk of bias within studies	12/19 (63%)	5/9 (56%)	7/10 (70%)
20	Results of individual studies	11/19 (58%)	5/9 (56%)	6/10 (60%)
21	Synthesis of results	16/19 (84%)	8/9 (89%)	8/10 (80%)
22	Risk of bias across studies	9/19 (47%)	5/9 (56%)	4/10 (40%)
23	Additional analysis	0/19 (0)	0/9 (0)	0/10 (0)
Discussion
24	Summary of evidence	19/19 (100%)	9/9 (100%)	10/10 (100%)
25	Limitations	16/19 (84%)	7/9 (78%)	9/10 (90%)
26	Conclusions	19/19 (100%)	9/9(100%)	10/10 (100%)
Funding
27	Funding	7/19 (37%)	3/9 (33%)	4/10 (40%)

Table 4 Meta-analyses of Observational Studies in Epidemiology criteria checklist

Checklist	Number	Papers meeting this standard (total number and percentage)	Published/ accepted papers meeting this standard (total number and percentage)	Preprint papers meeting this standard (total number and percentage)
I. Reporting of background
A. Problem definition		10/19 (53%)	7/9 (78%)	3/10 (30%)
B. Hypothesis statement		2/19 (11%)	1/9 (11%)	1/10 (10%)
C. Description of study outcome(s)		19/19 (100%)	10/9 (100%)	9/10 (90%)
D. Type of exposure or intervention used		18/19 (95%)	9/9 (100%)	8/10 (80%)
E. Type of study designs used		18/19 (95%)	9/9 (100%)	9/10 (90%)
F. Study population		18/19 (95%)	9/9 (100%)	9/10 (90%)
II. Reporting of search strategy
A. Qualifications of searchers		0/19 (0)	0/9 (0)	0/10 (0)
B. Search strategy		17/19 (89%)	9/9 (100%)	8/10 (80%)
C. Effort to include all available studies		10/19 (53%)	7/9 (78%)	3/10 (30%)
D. Databases and registries searched		17/19 (89%)	7/9 (78%)	10/10 (100%)
E. Search software used		8/19 (42%)	4/9 (44%)	4/10 (40%)
F. Use of hand searching		2/19 (11%)	1/9 (11%)	1/10 (10%)
G. List of citations located and those excluded		10/19 (53%)	5/9 (56%)	5/10 (50%)
H. Method of addressing articles published in languages other than English		0/19 (0)	0/9 (0)	0/10 (0)
I. Method of handling abstracts and unpublished studies		0/19 (0)	0/9 (0)	0/10 (0)
J. Description of any contact with authors		0/19 (0)	0/9 (0)	0/10 (0)
III. Reporting of methods
A. Description of relevance or appropriateness of studies assembled for assessing the hypothesis to be tested		8/19 (42%)	4/9 (44%)	4/10 (40%)
B. Rationale for the selection and coding of data		13/19 (68%)	7/9 (78%)	6/10 (60%)
C. Documentation of how data were classified and coded		12/19 (63%)	8/9 (89%)	4/10 (40%)
D. Assessment of confounding		1/19 (5%)	0/9 (0)	1/10 (10%)
E. Assessment of study quality		16/19 (84%)	7/9 (78%)	9/10 (90%)
F. Assessment of heterogeneity		18/19 (95%)	8/9 (89%)	10/10 (100%)
G. Description of statistical methods		19/19 (100%)	9/9 (100%)	10/10 (100%)
H. Provision of appropriate tables and graphics		18/19 (95%)	9/9 (100%)	9/10 (90%)
IV. Reporting of results
A. Graphic summarizing individual study estimates and overall estimate		19/19 (100%)	9/9 (100%)	10/10 (100%)
B. Table giving descriptive information for each study included		16/19 (84%)	7/9 (78%)	9/10 (90%)
C. Results of sensitivity testing (e.g, subgroup analysis)		12/19 (63%)	7/9 (78%)	5/10 (50%)
D. Indication of statistical uncertainty of findings		17/19 (89%)	8/9 (89%)	9/10 (90%)
E. Reporting of discussion should include
1. Quantitative assessment of bias (e.g, publication bias)		11/19 (58%)	4/9 (44%)	7/10 (70%)
2. Justification for exclusion (eg, exclusion of non–English-language citations)		3/19 (16%)	1/9 (11%)	2/10 (20%)
3. Assessment of quality of included studies		12/19 (63%)	4/9 (44%)	8/10 (80%)
V. Reporting of conclusions
A. Consideration of alternative explanations for observed results		1/19 (11%)	0/9 (0)	1/10 (10%)
B. Generalization of the conclusions (i.e, appropriate for the data presented and within the domain of the literature review)		19/19 (100%)	9/9 (100%)	10/10 (100%)
C. Guidelines for future research		8/19 (42%)	6/9 (66%)	2/10 (20%)