Allergic diseases as risk factors for Long‐COVID symptoms: Systematic review of prospective cohort studies

Abstract

ObjectiveThe role of allergy as a risk factor for Long‐COVID (LC) is unclear and has not been thoroughly examined yet. We aimed to systematically review and appraise the epidemiological evidence on allergic diseases as risk factors for LC.DesignThis is an initial systematic review. Two reviewers independently performed the study selection and data extraction using Covidence. Risk of bias (RoB) and certainty of evidence (GRADE) were assessed. Random effects meta‐analyses were used to pool unadjusted ORs within homogeneous data subsets.Data SourcesWe retrieved articles published between January 1st, 2020 and January 19th, 2023 from MEDLINE via PubMed, Scopus, the WHO‐COVID‐19 database and the LOVE platform (Epistemonikos Foundation). In addition, citations and reference lists were searched.Eligibility CriteriaWe included prospective cohort studies recruiting individuals of all ages with confirmed SARS‐CoV‐2 infection that were followed up for at least 12 months for LC symptoms where information on pre‐existing allergic diseases was available. We excluded all study designs that were not prospective cohort studies and all publication types that were not original articles.ResultsWe identified 13 studies (9967 participants, range 39–1950 per study), all assessed as high RoB, due to population selection and methods used to ascertain the exposures and the outcome. Four studies did not provide sufficient data to calculate Odds Ratios. The evidence supported a possible relationship between LC and allergy, but was very uncertain. For example, pre‐existing asthma measured in hospital‐based populations (6 studies, 4019 participants) may be associated with increased risk of LC (Odds Ratio 1.94, 95% CI 1.08, 3.50) and findings were similar for pre‐existing rhinitis (3 studies, 1141 participants; Odds Ratio 1.96, 95% CI 1.61, 2.39), both very low certainty evidence.ConclusionsPre‐existing asthma or rhinitis may increase the risk of LC.

Causal relationship between COVID-19 and the risk of asthma: A Mendelian Randomisation study

“…Wolff's research suggests that pre-existing asthma, measured in hospital-based populations, may be associated with an increased risk of Long COVID (Odds Ratio 1.94, 95% CI 1.08, 3.50). Similar associations were observed for pre-existing rhinitis (Odds Ratio 1.96, 95% CI 1.61, 2.39), with both pieces of evidence characterised as very low certainty 23 . Gerce's study revealed that eight weeks post-COVID-19 infection, some individuals still experienced symptoms such as cough and breathing di culties.…”

The Course of COVID-19 and Long COVID: Identifying Risk Factors among Patients Suffering from the Disease before and during the Omicron-Dominant Period

“…Regarding risk factors of long COVID, Bai et al’s research confirmed that females are at higher risk of developing long COVID [ 46 ], which is in line with the multicenter study by Fernández-de-Las-Peñas and colleagues [ 47 ]. A recent systematic review of prospective cohort studies by Wolff et al concluded that pre-existing asthma measured in a hospital-based population increases the risk of long COVID; however, the authors emphasized that this was assessed using low-certainty evidence related to population selection and exposure or outcome measurements [ 48 ].…”

Exploring the Pathophysiology of Long COVID: The Central Role of Low-Grade Inflammation and Multisystem Involvement

“…These issues have been addressed in review articles by other authors, including [ 285 , 319 , 320 , 321 , 322 ]. Another aspect of canonical inflammation in LC, which was not included in the aims and objectives of our study, is considering LC as a risk factor for the onset of various inflammatory diseases or the progression of existing inflammatory diseases [ 323 , 324 , 325 , 326 , 327 ]. This primarily concerns immune-dependent diseases, whose association has been established, namely various allergic, autoimmune, and infectious diseases, but also should be taken into account in other pathological conditions as well [ 237 , 238 , 239 , 240 , 241 , 242 , 243 , 244 , 245 , 246 , 247 , 248 , 249 , 250 , 251 , 252 , 253 , 254 , 255 , 256 , 257 , 258 , 259 , 260 , 261 , 262 , 263 , 264 , 265 , 266 , 267 , 268 , 269 , 270 , 271 , 272 , 273 , 274 , 275 ...…”