PONE-D-19-27025

CAUSES OF MORBIDITY AND MORTALITY IN A TERTIARY HOSPITAL IN SOUTHERN NIGERIA; A 6 YEAR EVALUATION

PLOS ONE

Dear Mr Okoroiwu,

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Academic Editor

PLOS ONE

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Reviewers' comments:

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Comments to the Author

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Reviewer #1: Partly

Reviewer #2: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: No

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The study is on the causes of morbidity and mortality in a tertiary hospital in Southern Nigeria and a retrospective work.

1. Being a retrospective work, were the authors able to verify accuracy of the diagnosis in each patient’s case notes to ascertain that the diagnosis was same as coded by the records? inputting wrong diagnosis is a common error in most hospitals in developing countries

2. The study was silent on missing data, a common problem with retrospective study.

3. To be more meaningful, the study should reclassify age groups of patients. The study lumped older children and young adult together which is not acceptable. Internationally, pediatric age group is from birth to <18 years; adults is 18 years to 64 years, and the elderly 65 years and above. This will allow for proper determination of leading cause of morbidity and mortality by age. Infectious diseases may not necessarily be the leading cause of morbidity and mortality among adults and elderly as concluded.

3. The study classified stroke as cardiovascular or circulation disease; Stroke is a cerebrovascular disorder and a neurological disorder and presently the leading cause of death in Nigeria like other developing countries. it is the commonest cause of disability. please reclassify stroke appropriately.

Reviewer #2: Given the paucity of data about in-hospital mortality and/or quality in many African countries, the paper does make a contribution to the literature. However, many points need to be clarified and/or expanded upon in order to increase the strength and interest of the article, as detailed below. The conclusions, particularly in the abstract, should also be more solidly explained as to their relation to the findings.

In addition, there are many mistakes in grammar which need to be corrected and I would recommend an editing service to review the manuscript.

Specific comments:

-Abstract conclusion: This does not give the reader a clear understanding of the main point/findings of the paper. It is very general. The meaning of "double burden of communicable and non-communicable diseases" needs to be specified. Also, if the authors wish to argue that most of the deaths in the study are preventable, this needs better supporting arguments in the discussion, as below.

-Methods: is this in-hospital mortality? If not, what duration of follow-up was used?

-Methods: should state whether this includes Labor and Delivery (see below corollary comment re: Discussion section)

-Methods: who determined the cause of death which is coded by ICD-10? The treating physician?

-Results: In the last line of the first paragraph, you stated that "mortality was significantly higher in female gender," however, the data suggest the opposite, and in the discussion section higher male mortality is discussed

-Results: Second paragraph, "647.0% of the patients were admitted via casualty"--the number needs to be correct to 0-100%

-Results: 5th paragraph: the text would be more informative/interesting with a description of what is meant specifically by "conditions originating from the perinatal period"

-Results: Description of which bacterial organisms the most common cause of septicemia would very much improve the strength

-Results: The last paragraph describes the percentage of deaths due to the leading causes listed.

(a) What does a death due to HIV/AIDS mean? Did these patients die from the virus itself (eg, wasting syndrome, etc.) or more likely, due to opportunistic infections? Again would be helpful to outline this more specifically, and if opportunistic infections, which ones?

(b) It would add significant strength and interest to the paper to know: Of the patients admitted with each of these conditions, what proportion died?

-Discussion: In the discussion of higher mortality among males, it would be important to know whether the female admissions/deaths include those admitted for labor and delivery, which would be expected to make the female mortality rate appear lower--eg, most would not be coming in "sick." If this did include L+D, would consider re-analyzing without those admissions to see if the difference in male and female mortality remains.

-Discussion: The commentary on males having less "health conscious" behavior than females seems somewhat like conjecture and should either be removed or re-stated using less definitive language (unless able to support with literature/data)

-Discussion: A rise in Hepatitis B and C is described. Would expand upon this more given that the finding of liver disease as one of the leading causes of death was the most surprising and potentially interesting piece of new information from the study. Can you specify rates of hepatitis viruses among those with liver disease who died in your study? If not, would describe if there are limitations in availability of testing. It would also be worthwhile to discuss how patients with these viral hepatitides are managed what at your facility and/or in Nigeria in general--are treatments available? Is this data suggesting a reason call for more specific resources for HBV and HCV?

-Discussion: the paragraph regarding conditions in the perinatal period and the Millenium Development Goals does not seem well-placed, and it is not clear how what is written here adds to the literature

-Discussion: Breast and liver cancer were described as leading causes of neoplasms, which is stated is consistent with previous findings. Previous findings from where? Similar hospital settings/LMIC's, etc? Should specify. Also, liver cancer as a leading neoplasm provides yet another opportunity to discuss more specifics about viral hepatitis, and connect to the above comments.

-Discussion: The argument that the mortality from infections and "conditions originating in the perinatal period" reflects low access to quality health care and reflects "amenable mortality" needs to be better supported and explained. As currently written, this reads as an assumption. Ideas include concepts such as: Preventable at what stage? If a patient presents with late-stage septic shock, just because there was an infectious cause does not necessarily mean this death could be prevented even with maximal quality of care at hospital presentation, etc.

-Discussion: I found the discussion about malaria as a cause of morbidity distracting, since the paper is focused on mortality

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Reviewer #1: Yes: Prof E.O. Sanya

Reviewer #2: No

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CAUSES OF MORBIDITY AND MORTALITY AMONG PATIENTS ADMITTED IN A TERTIARY HOSPITAL IN SOUTHERN NIGERIA; A 6 YEAR EVALUATION

PONE-D-19-27025R1

Dear Dr. Okoroiwu,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Kind regards,

Chiara Lazzeri

Academic Editor

PLOS ONE

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