Coronavirus disease 2019 complications in patients with hidradenitis suppurativa: A multicenter analysis.

Dear Editor,

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disorder consisting of painful nodules and abscesses in areas of apocrine gland‐bearing skin. While not established as a predictor for complications in coronavirus disease 2019 (COVID‐19) itself, HS is associated with other comorbidities including diabetes, smoking, and obesity, as well as racial minorities, which may predispose to poor COVID‐19 outcomes. We aimed to investigate the effect of HS on COVID‐19 complications to account for these comorbidities.

In this study, patients aged 18 years or more diagnosed with COVID‐19 (between 20 January 2020 and 30 March 2021) were identified via real‐time search and analysis of more than 68 million patients from 48 health‐care organizations participating in TriNetX, a global federated database. Patients infected with COVID‐19 (confirmed using criteria recommended by the World Health Organization) were divided into two groups based on the presence or absence of HS, identified via validated International Classification of Diseases, 10th Revision (ICD‐10) codes prior to the date of COVID‐19 diagnosis.

The primary outcome was 30‐day all‐cause mortality post‐COVID‐19 diagnosis. Secondary outcomes were the need for mechanical ventilation, hospitalization, acute respiratory distress syndrome, sepsis, and severe COVID (composite of mortality and ventilation). A 1:1 matched propensity score analysis was conducted, adjusting for comorbidities and demographics, to calculate adjusted risk ratios (aRR) with 95% confidence intervals (CI). The greedy nearest‐neighbor matching algorithm was used to balance baseline characteristics between the cohorts. Subgroup analyses were also performed for HS patients treated with systemic antibiotics for their anti‐inflammatory effects (defined as any 1‐year history use of rifampin, metronidazole, tetracyclines, or moxifloxacin) and HS patients treated with tumor necrosis factor (TNF) inhibitors (any 1‐year history use of adalimumab, infliximab, certolizumab pegol, golimumab, and etanercept) versus those without. All statistical analyses were performed using TriNetX with standard methodology as previously reported. Reported data was deidentified with no protected health information and thus was exempt from the institutional review board.

A total of 643 025 patients with COVID‐19 were identified, 2600 with HS and 640 425 without. The cohort with HS was younger and had a higher proportion of females, black subjects, and comorbidities. Matching formed two well‐balanced groups of 2598 patients. There were no significant differences between COVID‐19 patients with and without HS in any outcomes after matching (e.g., mortality aRR, 0.69 [95% CI, 0.6–1.8]; p = 1.00). Of the HS patients, 44% had a 1‐year history of systemic antibiotic use and subgroup analyses revealed no significant differences in COVID‐19 outcomes when compared to those without 1‐year history of antibiotic use (Table 1), while 3.4% had a 1‐year history of TNF inhibitor use and similarly, no significant differences in complications were seen compared to those without 1‐year history of TNF inhibitor use.

TABLE 1

Baseline characteristics and outcomes of COVID‐19 patients with and without HS

	Baseline characteristics
	Before propensity matching		p	After propensity matching		p
	HS‐COVID‐19 (n = 2600)	No HS‐COVID‐19 (n = 640 425)		HS‐COVID‐19 (n = 2598)	No HS‐COVID‐19 (n = 2598)
Mean age at index (±SD)	42 ± 15	48 ± 19	<0.001	42 ± 15	42 ± 15	0.409
Obesity	1262 (49%)	78 099 (12%)	<0.001	1260 (49%)	1269 (49%)	0.803
White	1252 (48%)	402 897 (63%)	<0.001	1252 (48%)	1251 (48%)	0.978
Female	2088 (80%)	353 786 (55%)	<0.001	2086 (80%)	2084 (80%)	0.944
Black	1041 (40%)	103 113 (16%)	<0.001	1039 (40%)	1068 (41%)	0.413
Essential (primary) hypertension	1157 (45%)	163 887 (26%)	<0.001	1155 (45%)	1153 (45%)	0.956
Chronic lower respiratory diseases	1028 (40%)	97 447 (15%)	<0.001	1026 (39%)	1035 (40%)	0.799
Ischemic heart diseases	278 (11%)	49 632 (8%)	<0.001	278 (11%)	261 (10%)	0.439
Diabetes mellitus	770 (30%)	79 484 (12%)	<0.001	768 (30%)	758 (30%)	0.761
CKD	224 (9%)	34 048 (5%)	<0.001	224 (9%)	2109 (8%)	0.451
Cerebrovascular diseases	162 (6%)	30 022 (5%)	<0.001	162 (6%)	147 (6%)	0.379
Heart failure	212 (8%)	28 131 (4%)	<0.001	212 (8%)	185 (7%)	0.159
Nicotine dependence	670 (26%)	47 999 (8%)	<0.001	668 (26%)	663 (26%)	0.874
Alcohol‐related disorders	148 (6%)	16 303 (3%)	<0.001	146 (6%)	139 (5%)	0.670

Counts ≤ 10 are obfuscated to 10 to protect patient privacy.

Abbreviations: ARDS, acute respiratory distress syndrome; CI, confidence interval; CKD, chronic kidney disease; COVID‐19, coronavirus disease 2019; HS, hidradenitis suppurativa; SD, standard deviation.

Drugs (systemic antibiotics): any 1 year history use of rifampin, metronidazole, tetracyclines, moxifloxacin.

It has been postulated that patients with HS are at higher risk for adverse COVID‐19 outcomes; however, this has not been previously demonstrated. Lima et al. conducted a medical records analysis (although without matching) and did not show increased risk of hospitalization, intensive care admission or death due to COVID‐19 in patients with HS versus those without; while Galán et al. reviewed the records of 75 HS patients and observed no severe COVID‐19 cases or deaths in a region heavily affected at the time. Similarly, in our analysis, outcomes of COVID‐19 were not significantly different between patients with and without HS after matching. However, further studies examining the long‐term effects of COVID‐19 in patients with HS are warranted. Prior research suggests that systemic immunosuppression is not associated with worse COVID‐19 outcomes. Similarly, our analysis showed that HS patients treated with systemic antibiotics or TNF inhibitors were not at higher risk of COVID‐19 complications. Limitations of this study include possible errors with coding entry, a bias towards sicker patients who got tested, an inability to track clinical course, and no data regarding HS severity since only ICD‐10 codes were recorded.

This finding supports the continued use of these medications to manage HS during the current pandemic and may alleviate concerns that their anti‐inflammatory or immunosuppressive effects can confer worse COVID‐19 outcomes.

CONFLICT OF INTEREST

None declared.