Hundreds of articles have been published over the last six months, making well-meaning attempts to determine whether patients with different comorbidities are more susceptible for SARS-CoV-2 infection or at higher risk for severe disease. This deluge of scientific publications has resulted in worldwide uncertainty. For a number of reasons, many studies must be interpreted with extreme caution.
First, in many articles, the number of patients with specific comorbidities is low. Small sample sizes preclude accurate comparison of COVID-19 risk between these patients and the general population. They may also overestimate mortality, especially if the observations were made in-hospital (reporting bias). Moreover, the clinical manifestation and the relevance of a condition may be heterogeneous. Is the hypertension treated or untreated? What is the stage of the COPD, only mild or very severe with low blood oxygen levels? Is the “cancer” cured, untreated or actively being treated? Are we talking about a seminoma cured by surgical orchiectomy years ago or about palliative care for pancreatic cancer? What is a “former” smoker: someone who decided to quit 20 years ago after a few months puffing during adolescence or someone with 40 package-years who stopped the day before his lung transplantation? Does “HIV” mean a well controlled infection while on long-lasting, successful antiretroviral therapy or an untreated case of AIDS? Unfortunately, many researchers tend to combine these cases, in order to get larger numbers and to get their paper published.Second, there are numerous confounding factors to consider. In some case series, only symptomatic patients are described, in others only those who were hospitalized (and who have per se a higher risk for severe disease). In some countries, every patient with SARS-CoV-2 infection will be hospitalized, in others only those with risk factors or with severe COVID-19. Testing policies vary widely between countries. The control group (with or without comorbidities) is not always well-defined. Samples may not be representative, risk factors not correctly taken into account. Sometimes, there is incomplete information about age distribution, ethnicity, comorbidities, smoking, drug use and gender (there is some evidence that, in female patients, comorbidities have no or less impact on the course of the disease, compared to male (Meng 2020)). All these issues present important limitations and only a few studies have addressed all of them.
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Third, comorbidity papers have led to an information overload. Yes, virtually every medical discipline and every specialist has to cope with the current pandemic. And yes, everybody has to be alert these days, psychiatrists as well as esthetic surgeons. Hundreds of guidelines or position papers have been published, trying to thoughtfully balance fear of COVID-19 against the dire consequences of not treating other diseases than COVID-19 in an effective or timely manner – and all this in the absence of data. On May 15, a PubMed search yielded 530 guidelines or considerations about specific diseases in the context of COVID-19, among them those for grade IV glioma (Bernhardt 2020, bottom line: do not delay treatment), but also for dysphonia and voice rehabilitation (Mattei 2020: can be postponed), infantile hemangiomas (Frieden 2020: use telehealth), ocular allergy (Leonardi 2020: very controversial), high resolution anoscopy (Mistrangelo 2020: also controversial), migraine management (Szperka 2020: use telehealth) and breast reconstruction (Salgarello 2020: defer “whenever possible”), to name just a few. These recommendations are usually not helpful. They apply for a few weeks, during acute health crisis scenarios as seen in overwhelmed health care systems in Wuhan, Bergamo, Madrid or New York. In other cities or even a few weeks later, proposed algorithms are already outdated. Nobody needs a 60-page recommendation, concluding that “clinical judgment and decision making should be exercised on a case-by-case basis”.
However, some important papers have been published during the last months, a couple of them with very helpful data, supporting the management of patients with comorbidities. In the following, we will briefly go through these.