We read with interest the study by Khan et al regarding the incidence and impact of IBD medications on risk of pneumonia and pneumonia-related hospitalisation.1 We compliment the authors for their effort to address the paucity of data on infections such as pneumonia in the IBD population. Using the nationwide Veterans Affairs database, they found incidence rates of 6.47 and 2.52 per 1000 person-years (PY) for pneumonia and pneumonia-related hospitalisations, respectively.

The strict definition for pneumonia events in their study has ensured the inclusion of clinically relevant cases ( i.e., more severe cases) of pneumonia, but may have led to under-reporting of milder infectious events. The choice to include a positive chest X-ray in their definition might also have led to variable sensitivity rates.2 Although mild-to-moderate lower respiratory tract infections (LRTIs) are generally associated with low morbidity and mortality rates, they can have negative effects on patients' quality of life and perceived health, lead to increased healthcare costs and decreased societal participation. Reporting differences in all infections is important when addressing the real burden of treatment options in IBD.

To add further insight on the prevalence of these infections, we share our real-world multicentre experience with the IBD population in South Limburg based on data collected using myIBDcoach, an established telemedicine platform for IBD management, which contains several patient-reported outcome measures and remote monitoring tools, including periodic assessment of infectious events.3 In 600 IBD patients (mean age at cohort entry 49.7 [SD 14.9]; n = 342 Crohn’s disease [59.9% female]; n = 258 ulcerative colitis [47.7% female]), included between 1 January 2020 and 1 January 2021, we observed 43 LRTIs during follow-up (including pneumonia, excluding COVID-19). Of these, 16 were mild (i.e., either requiring no treatment or analgesics), 25 moderate (i.e., requiring oral antibiotics) and two severe ( i.e., hospitalisation or intravenous antibiotics), corresponding to incidence rates of 2.5, 4.0 and 0.3 per 100 PY, respectively (Table 1). All events were cross-checked with GP and pharmacy data, and no LRTI-related deaths were observed. Representativeness of this subset of patients for the real-world situation was established by comparing demographics (age, sex, smoking) and clinical characteristics (Montreal classification) to the total IBD population in South-Limburg.4

TABLE 1. Incidence rates for lower respiratory tract infections (LRTIs) per 100 PY All infections Mild infections Moderate infections Severe infections n IR (95% CI) n IR (95% CI) n IR (95% CI) n IR (95% CI) Infection type LRTIs 43 6.8 (5.0-9.1) 16 2.5 (1.5-4.0) 25 4 (2.6-5.8) 2 0.3 (0.05-1.1) Note Since the remote monitoring tool periodically assesses infections in the 3 months prior, follow-up period is slightly longer than 1 year. Abbreviations: CI, confidence interval; IR, incidence rate; n, number of events; PY, person-years;95% CI calculated using the Mid-P exact test. Time at risk (630.59 PY) based on follow-up of 600 IBD patients.

We acknowledge the smaller sample size when compared to the study of Khan et al and understand that their study design did not allow for capturing milder infections. However, the rates observed in our study, especially for moderate infections (requiring antibiotics), are substantially higher than those observed by Khan et al, which cannot only be explained by potential other causes of LRTIs in our cohort. Data on mild and moderate infections in medically treated IBD patients remain scarce and the most plausible explanation is that events treated by general practitioners are not systematically captured in surveillance registries. Our data particularly underscore that, in a real-world population of IBD patients, a substantial proportion of LRTIs follow a mild-to-moderate course. Remote monitoring tools designed to periodically assess infectious events could overcome the paucity of data regarding mild and moderate infections.

ACKNOWLEDGEMENT

Declaration of personal interests: A. Rezazadeh Ardabili and Z. Mujagic have nothing to declare. D. Jonkers has received research funding from Top Knowledge Institute (Well on Wheat), Horizon 2020 DISCOvERIE, and NWO-CCC Partnership program (Carbokinetics), all outside the submitted work. M.J. Pierik has served on advisory boards, as speaker or consultant for Abbvie, Janssen-Cilag, MSD, Takeda, Ferring, Dr. Falk and Sandoz, and has received research funding from Janssen-Cilag, Abbvie and Takeda, all outside the submitted work.

Declaration of funding interests: This study was in part funded with an investigator-initiated research grant by Takeda (2019-102915).

ETHICAL APPROVAL

This study was approved by the medical ethics committee (MEC) of Maastricht University and Maastricht University Medical Center+ (MUMC+)(study reference: 2019-1115). All patients included in the study provided written informed consent.