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Review 2: "Healthcare Utilisation of 282,080 Individuals with Long COVID over Two Years: A Multiple Matched Control Cohort Analysis"

Both authors found that this preprint seemed reliable and had appropriate methodology for the primary research question, though recommended more details to be provided in the Methods section.

Published onFeb 20, 2024
Review 2: "Healthcare Utilisation of 282,080 Individuals with Long COVID over Two Years: A Multiple Matched Control Cohort Analysis"

RR:C19 Evidence Scale rating by reviewer:

  • Reliable. The main study claims are generally justified by its methods and data. The results and conclusions are likely to be similar to the hypothetical ideal study. There are some minor caveats or limitations, but they would/do not change the major claims of the study. The study provides sufficient strength of evidence on its own that its main claims should be considered actionable, with some room for future revision.



The authors of this article claim that individuals with Long COVID (LC) experience higher healthcare utilization over 2 years relative to a COVID-19, no LC group, a pre-long COVID-19 group, a contemporary non-COVID group and a pre-pandemic group whereas the highest medical expenditures are reported for the COVID-19, no LC group. The authors highlight that the bulk of the healthcare burden occurs within the first two months post-diagnosis which may reflect more severe viral load following infection or increased clinical examination.

This study provides novel evidence of healthcare utilization and medical expenditures of a large patient cohort patients diagnosed with LC in the UK over an comparably extended period of time to pre-existing literature. The authors compare LC patients with their pre-pandemic values, post-pandemic information of patients with no COVID-19 or COVID-19, but no LC defined as "control groups". 

This research study makes a significant contribution to the existing literature by providing fresh insights into the healthcare utilization and cost implications related to a large patient cohort diagnosed with Long COVID (LC) in the UK over an extended period of time, notably longer than in most previous studies. The researchers intelligently compared healthcare utilization and cost data of LC patients with data from control groups - both their own pre-pandemic healthcare utilization and cost data, and information from patients in the post-pandemic period, with some having not contracted COVID-19 and others having had COVID-19 but not developing LC. This comparative approach lends to multiple set of results that increase the contributions of the paper but also the need for increased clarity in discussion of the results.

The methodology utilized for this research study, on the whole, appears to be sound and appropriate for the type of investigation carried out by the researchers. The authors acknowledge both the strengths and limitations of their study but are encouraged to explicitly mention the omission of telehealth visits in conjunction with telephone consultations in their data.

Major comments:

  1. Firstly, the utilization of multiple "control groups" in the same study can be confusing and potentially unclear. It would likely be more beneficial for the authors to decide on a single control group to use as the primary comparison benchmark, and then produce baseline results relative to this group. Given that there has been an overall increase in healthcare utilization compared to pre-pandemic times, choosing the 'contemporary non-COVID' group as the principal reference group for baseline results could provide a more insightful comparison. Findings from alternative comparisons could be presented as supplementary data in the form of sensitivity analyses. Specifically, the comparisons involving COVID-19 only, no LC and pre-long COVID patients could then be used for sensitivity analysis.

  2. The authors should elaborate more on the discrepancy noted between the group that recorded the highest healthcare utilization and the highest healthcare costs. Could this discrepancy be driven by mortality? That is, are healthcare costs higher for the COVID-19 only, no LC group due to potentially more intensive care required to the LC patients? Additionally, is the higher and more persistent healthcare utilization reported for the LC patients merely a token of the fact these patients survived COVID-19 to be in the position to utilize additional healthcare services over time?

Minor comments:

On a minor note, it may be beneficial for the authors to consider referring to the "control groups" as "comparison groups". The usage of the term "comparison groups" can help to eliminate any potential misinterpretation of the research study's intent. It is not uncommon to use a single control group and multiple, distinct treatments.

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