The Methodological Quality of Case Series Published Early vs. Late in the Course of a Pandemic: A Meta-Epidemiologic Study

Abstract

Introduction Case reports and series are critical to guide initial decision-making in a pandemic, but may have lower rigor because of the need to publish them quickly. This meta-epidemiologic study compares the methodological quality of case series that described the acute coronavirus disease 2019 (COVID-19) pandemic in 2020 versus those that described long-haul cases.

Methods We conducted a systematic review in multiple databases for long-haul case series and reports. We identified early cases of acute COVID-19 synthesized in published systematic reviews. We evaluated the methodological quality by pairs of independent reviewers using a tool dedicated for appraising case series.

Results We included 239 original case series (81 published in the first year of the pandemic and 158 published later describing long-haul COVID). The methodological quality of both groups of case series was very good (80–100% of series satisfying quality items) except for two items, the selection approach of cases included in the series and ruling out other causes that can explain the main finding described in the series. The appraisal tool demonstrated high agreement and reliability between reviewers.

Conclusion The methodological quality of modern case series is high, except for two quality items that represent an area for potential for improvement for authors of case series describing future pandemics.

Keywords

methodological quality - risk of bias - meta-epidemiological research - case series - case reports

Ethical Approval and Consent to Participate

None.

Consent for Publication

None.

Availability of Supporting Data

Data are available from the corresponding author upon reasonable request.

Authors' Contributions

M.H.M., Y.A., and S.S. conceived this study. M.E.W. and G.V. provided clinical content expertise. M.F., T.N., M.O.S., R.A.A., A.S.A., E.H.L., Y.Z., and L.J.P. participated in data identification, extraction, and analysis. M.H.M., Y.A., and S.S. wrote the first draft. All authors critically revised the manuscript and approved the final version.

Authors' Information

None.

Publikationsverlauf

Artikel online veröffentlicht:
02. April 2025

• References

• 1 Herrick J. Peculiar elongated and sickle-shaped red blood corpuscles in a case of severe anemia. Arch Intern Med (Chic) 1910; VI [phone]
• 2 Centers for Disease Control (CDC). Pneumocystis pneumonia–Los Angeles. MMWR Morb Mortal Wkly Rep 1981; 30 (21) 250-252
• 3 Huang C, Wang Y, Li X. et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet 2020; 395 (10223): 497-506
• 4 Murad MH, Wang Z. Guidelines for reporting meta-epidemiological methodology research. Evid Based Med 2017; 22 (04) 139-142
• 5 Murad MH, Sultan S, Haffar S, Bazerbachi F. Methodological quality and synthesis of case series and case reports. BMJ Evid Based Med 2018; 23 (02) 60-63
• 6 Khan S, Gionfriddo MR, Cortes-Penfield N, Thunga G, Rashid M. The trade-off dilemma in pharmacotherapy of COVID-19: systematic review, meta-analysis, and implications. Expert Opin Pharmacother 2020; 21 (15) 1821-1849
• 7 Knisely A, Wu J, Kaplan SJ. et al. Coronavirus spectrum infections (COVID-19, MERS, SARS) in cancer patients: a systematic review of the literature. Cancer Invest 2020; 38 (8-9): 436-444
• 8 Huntley BJF, Huntley ES, Di Mascio D, Chen T, Berghella V, Chauhan SP. Rates of maternal and perinatal mortality and vertical transmission in pregnancies complicated by severe acute respiratory syndrome coronavirus 2 (SARS-Co-V-2) infection: a systematic review. Obstet Gynecol 2020; 136 (02) 303-312
• 9 Ashraf MA, Keshavarz P, Hosseinpour P. et al. Coronavirus disease 2019 (COVID-19): a systematic review of pregnancy and the possibility of vertical transmission. J Reprod Infertil 2020; 21 (03) 157-168
• 10 Di Mascio D, Khalil A, Saccone G. et al. Outcome of coronavirus spectrum infections (SARS, MERS, COVID-19) during pregnancy: a systematic review and meta-analysis. Am J Obstet Gynecol MFM 2020; 2 (02) 100107
• 11 Kaushik A, Gupta S, Sood M, Sharma S, Verma S. A systematic review of multisystem inflammatory syndrome in children associated with SARS-CoV-2 infection. Pediatr Infect Dis J 2020; 39 (11) e340-e346
• 12 Bastola A, Nepal R, Shrestha B. et al. Persistent symptoms in post-COVID-19 patients attending follow-up OPD at Sukraraj Tropical and Infectious Disease Hospital (STIDH), Kathmandu, Nepal. Trop Med Infect Dis 2021; 6 (03) 113
• 13 Mølhave M, Leth S, Gunst JD. et al. Long-term symptoms among hospitalized COVID-19 patients 48 weeks after discharge-a prospective cohort study. J Clin Med 2021; 10 (22) 5298
• 14 Vanichkachorn G, Newcomb R, Cowl CT. et al. Post-COVID-19 syndrome (long haul syndrome): description of a multidisciplinary clinic at Mayo Clinic and characteristics of the initial patient cohort. Mayo Clin Proc 2021; 96 (07) 1782-1791
• 15 Schünemann HJ, Cook D, Guyatt G. Methodology for antithrombotic and thrombolytic therapy guideline development: American College of Chest Physicians Evidence-based Clinical Practice Guidelines (8^th Edition). Chest 2008; 133 (06) 113S-122S
• 16 Dekkers OM, Egger M, Altman DG, Vandenbroucke JP. Distinguishing case series from cohort studies. Ann Intern Med 2012; 156 (1 Pt 1): 37-40
• 17 Mathes T, Pieper D. Clarifying the distinction between case series and cohort studies in systematic reviews of comparative studies: potential impact on body of evidence and workload. BMC Med Res Methodol 2017; 17 (01) 107