How many patients does case series should have? In comparison to case reports – Pubrica

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How Many Patients does Case Series Should

Have. In Comparison to Case Reports

Dr. Nancy Agnes, Head, Technical Operations, Pubrica, [email protected]

Keywords: Physician writing, Case Reporting, Case

Report Writing Services, medical case study report

writing, help in case study writing, case study report

writing, case report writing help

In-Brief

The medical research field is continuously

expanding, with more amount of data, being

generated every day. In clinical research, several

studies have been classified into descriptive and

analytic studies. Descriptive studies include cross-

sectional studies, ecological correlational studies,

case reports writing, case series report writing and

surveillance studies. On the other hand, analytical

studies examine a hypothesis about a causal

relationship between exposure and outcome. Since

the objective of this article is on case report and case

series, the analyses would be restricted only to those

type of studies alone.

I. INTRODUCTION

A case series and case reports consist of either of

aggregate of individual cases in one publication on

the diagnosis and treatment or a report of a single

patient. A high number of case reports been received

for publication, but it seems the rejection rate of CRs

is quite high across many journals. This is because,

according to the principle of evidence-based

medicine, they provide a lower strength of evidence

among clinical studies, as shown in Figure 1. Out of

two different forms of clinical research studies – (i)

descriptive and (ii) analytic, case series (CS) and case

reports (CR) fall under descriptive one. In specific,

case reports/series are usually retrospective and

occasionally be prospective, such as the Herrick’s

first case report of sickle cell disease.

II. WHEN TO CONSIDER A CASE SERIES

If you intend to publish your case reports and case

series, remember your reports should be the first

document medical breakthroughs i.e., reporting of

rare diseases in identifying adverse or beneficial

outcomes of intervention or novel diagnostic or

therapeutic strategies. Further, the primary purpose

was to generate hypotheses that can be subsequently

tested in studies of greater methodological rigour.

Therefore, case series can be applied to assess the

treatment safety and diagnostic accuracy, and in fact,

no control group is necessary with good long-term

follow-up. In order to get your research to be funded,

there is a need for preliminary evidence on which to

base the belief that a treatment may be efficacious. In

this case, these reports often provide the first level of

evidence. A study published in the Journal of

Clinical Epidemiology examined the case reports and

case series published in The Lancet Journal. The

study demonstrated that case series that are carefully

designed and, of course, similar to clinical trials are

likely to minimize bias and maximize the information

that can be deduced from a limited number of

patients.

Besides, in order to publish your reports, need to

ensure that both case series and reports have to follow

a standard structure and methodological rigour with

reference to selection, ascertainment, casualty and

reporting. The following section highlights the

difference between these two reports and possible

ways to get it published in High impact journals.

III. WHEN HIGH ACCEPTANCE RATE IS

POSSIBLE

Difference between a case series and a case report

A case series in general carries information acquired

from various sources containing one or more

information about the disease, treatment, diagnostic

methods, etc., whereas a case report contains a very

less amount of data and may contain in-depth

demographical details. It takes more time to accept

the case series than the time taken to accept the case

report by any publisher.

Case reports are professional narratives that

offer feedback on clinical practice guidelines and

provides a framework for adverse events, initial

signals of effectiveness, and cost. They can be shared

for medical, scientific, or educational purposes.

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Figure 1. Evidence Pyramid (RCT=randomised controlled trial, SR=Systematic review,

MA=metaanalysis) Source: http://www.aub.edu.lb/libraries/medical/ues/cochrane_evidence.htm

IV. SUBJECTS IN CASE SERIES AND CASE

REPORT

Many publishers strongly stick to the count of the

patients reported in the study. After the study reports,

[1] suggested that a case report contain patients of

less than five individuals, whereas a case series can

contain four and more patients. Few journals have no

upper limit set for the case series; other journals

accept nearly 20 patients report as a single case

series.

Table 1: Role of case reports/series in the medical literature

Roles Examples

Describe a new phenotype or genotype of the disease The first case report of sickle cell disease.

Recognize a known or common manifestation of a rare

disease

Liver cirrhosis as a result of Sitosterolaemia.

Recognize a rare manifestation of a known or common

disease

Secretory diarrhoea and hypokalemia in colonic

pseudo-obstruction.

Describe a new pathogen (microbe, virus or The Discovery of AIDS was an observation of a

http://www.aub.edu.lb/libraries/medical/ues/cochrane_evidence.html


environmental

exposure)

patient with immunodeficiency-related diseases who

otherwise had no reason to be immunodeficient.

Describe the unknown adverse effect of an existing

drug

Reye syndrome and aspirin in children.

Thalidomide and malformation of the limbs in

pregnant women

Describe a novel treatment for a known condition Colchicine for the treatment of familial Mediterranean

fever.

Elucidate mechanisms of disease Functional imaging of the brain during auditory

hallucinations.

To remind or educate Case presentations in clinic pathological conferences

for postgraduate education.

V. MERITS AND DEMERITS

Both case series and case report writing have their

merits and demerits. Case series is very useful in rare

case scenarios where a new kind of disease or

disorder harms the subject. Also, the publishers may

make few negotiations in considering a case series

due to the biased contents based upon the editors'

personal opinions. Besides, case series has high

external validity, no interference in treatment

decision process, wide range of patients and finally

inexpensive. In terms of limitations, the study lack of

comparison groups, data collection often be

incomplete, susceptible to bias, selection and

measurement bias. On the other hand, case reports

help healthcare professionals easily understand the

cases and take less time to be prepared. But case

reports may not possess all the relevant and minute

details to treat the subjects. No randomisation is

followed in a case series; therefore, it becomes more

efficient and affordable.

VI. CRITERIA

Whenever a case series is getting developed, few

criteria need to be followed.

(i) Title – Remember to include the words ―case series‖ and the area of focus in the title

(ii) Abstract’ – Introduction - Unifying theme of the case series should be emphasized

a. Methods – what was done, how and when.

b. Results – what was found. c. Conclusion – what we have learned.

(iii) Introduction – emphasize the scientific background and rationale.

(iv) Design –the research registry number (ResearchRegistry.com or ClinicalTrials.gov

or ISRCTN), list the intended population,

process manner, and end outcome. There

must be a proper method to acquire the data

like regular telephone calls, clinical

observation, and more. Study design should

be sated including prospective, retrospective

in design. Also, enough time should be

given between continuous follow-ups. Not a

case series would be attractive when taking

the subject cases that last more than a year

because increasing the period may lead to

disruption of study in the middle due to any

unexpected situations like the patient would

die or relocate his/her place or change the

hospital.

(ii) Analysis – Descriptive statistics and

methodologies must be used while analysing and no

comparative tests yielding p values should be carried

out.

(iii) Reporting – A case series must report the subject

details and progress, complete details, and analyse

every follow-up. There must be no declared

conclusions at the end because once a valid

conclusion is declared, it makes the investigators

keep on updating the results by comparing with other

results, which develops a need for hypothesis testing.

The researcher must understand the limitations before

getting engaged and possess awareness about the

conclusions.

Pubrica has extensive experience in

developing a detailed clinical case report Writing

Services that assist in highlighting the scientific

documentation.

VII. CONCLUSION

Both case series and case reports in the clinical

research field are meant to be utilized by healthcare

professionals. Except for the distinguishing features

between a case series and a case report, they both

tend to give valid information with timely

intervention. If both are well prepared from the initial

stages, they can even be alternatives to another level

of studies employed more confidently than the

former. Reporting case series in a standardized and

statistically appropriate manner would allow for

proper interpretation at the same time enable to

conduct of future meta-analyses to produce estimates

for the long-term outcomes.

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Table 2: Tool for evaluating the methodological quality of case reports and case series[6]

REFERENCES

1. Konala, V. M., Adapa, S., Naramala, S., Chenna, A., Lamichhane, S., Garlapati, P. R., ... &Gayam,

V. (2020). A case series of patients coinfected

with influenza and COVID-19. Journal of

investigative medicine high impact case

reports, 8, 2324709620934674.

2. Tahvildari, A., Arbabi, M., Farsi, Y., Jamshidi, P., Hasanzadeh, S., Calcagno, T. M., ...

&Mirsaeidi, M. (2020). Clinical features,

diagnosis, and treatment of COVID-19 in

hospitalised patients: a systematic review of case

reports and case series. Frontiers in medicine, 7,

231.

3. Suhling, H., Welte, T., &Fuehner, T. (2020). Three Patients With Acute Pulmonary Damage

Following the Use of E-Cigarettes—A Case

Series. DeutschesÄrzteblatt

International, 117(11), 177.

Domains Leading explanatory questions

Selection

1. Does the patient(s) represent(s) the whole experience of the

investigator (centre), or is the selection method unclear to the extent

that other patients with the similar presentation may not have been

reported?

Ascertainment 2. Was the exposure adequately ascertained?

3. Was the outcome adequately ascertained?

Causality

4. Were other alternative causes that may explain the observation

ruled out?

5. Was there a challenge/rechallenge phenomenon?

6. Was there a dose-response effect?

7. Was follow-up long sufficient for outcomes to occur?

Reporting

8. Is the case(s) described with sufficient details to allow other

investigators to replicate the research or to allow practitioners to make

inferences related to their own practice?

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