Low rate of seroconversion analyzing QuantiFERON TB-gold testing in patients with psoriasis and hidradenitis suppurativa taking biologic therapy at an academic center in New York City

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To the Editor: Current guidelines advise tuberculosis (TB) baseline screening before initiating biologic medications, due to risk of latent tuberculosis infection reactivation, with varying recommendations on repeat screening. Studies analyzing screening in US cities with high TB rates are lacking. We aimed to stratify utility of serial QuantiFERON TB-gold (QFT) testing in patients with psoriasis or hidradenitis taking biologic treatment for hidradenitis suppurativa in New York City (NYC), which has high TB burden.

Weill Cornell Medical Center’s EPIC database was queried March 23, 2011 to July 21, 2023 for psoriasis or patients with hidradenitis suppurativa with ages ≥18 years treated with a biologic, with ≥2 QFT test results, with ≥1 prior to treatment. Wilcoxon rank-sum tests evaluated mean ages and number of risk factors between seroconverters and nonseroconverters (P < .05). Receiver operating characteristic analysis with Youden index identified optimal age cutoff for seroconversion risk.

A total of 356 patients were included (Table I). Overall, 71.6% of patients resided in NYC, (TB burden 6.1 cases/100,000 people), and 90.1% lived within the New York-Newark-Jersey City metropolitan statistical area (top 10% for TB burden among all metropolitan statistical area’s with >500,000 residents in 2021, 4.2/100,000).1 Patients underwent mean 3 QFT tests (range: 2-12) (Supplementary Table I, available via Mendeley at https://data.mendeley.com/datasets/t4mj454jwy/1). Five patients seroconverted (1.4%), and 2 had negative repeat testing and were considered false positives on their second and fifth tests, respectively (0.6%). There were 3 true seroconverters (0.8%), all seroconverting on their second test. True seroconverters were older, on average, than other subjects (73 and 45.7 years, P < .008) and had greater numbers of TB risk factors (4.67 and 1.86, P = .0178) (Supplementary Table II, available via Mendeley at https://data.mendeley.com/datasets/t4mj454jwy/1). Sixty-six years old was the cutoff for increased seroconversion risk (receiver operating characteristic analysis, Youden). No seroconverters resided in high-TB risk neighborhoods (Table II). All 3 true seroconverters were treated for latent tuberculosis infection and none developed active TB.Table IPatient demographics, treatment details, and QuantiFERON TB-gold testing outcomesDemographic characteristicn (%)Number of patients356Age (y), mean (Q1-Q3)46.0 (32.0-59.0)Sex, n (%) Male164 (46.1) Female192 (53.9)Race, n (%) White138 (38.8) Other97 (27.2) Declined56 (15.7) Black or African American46 (12.9) Asian19 (5.3)Ethnicity, n (%) Not Hispanic, Latino, or Spanish origin170 (47.8) Hispanic, Latino, or Spanish origin101 (28.4) Declined85 (23.9)Geographic distribution by state, n (%) NY301 (84.5) NJ41 (11.5) Others∗14 (3.9)Geographic distribution within NY, n (%) Manhattan113 (31.7) Queens53 (14.9) Bronx45 (12.6) Brooklyn41 (11.5) Staten Island3 (0.8) Total within New York City (NYC)255 (71.6) High tuberculosis risk zip code†18 (5.1)Treatment, n (%) Adalimumab120 (33.7) Ustekinumab61 (17.1) Secukinumab48 (13.5) Risankizumab42 (11.8) Infliximab33 (9.3) Etanercept20 (5.6) Guselkumab17 (4.8) Ixekizumab15 (4.2) Abatacept3 (0.8) Certolizumab3 (0.8) Tildrakizumab2 (0.6) Vedolizumab1 (0.3) Dupilumab1 (0.3)Indication, n (%) Psoriasis321 (90.2) Hidradenitis suppurativa35 (9.8)Number of tests per patient, median (Q1-Q3)3 (2-4)Time between first and last test (mo), median (Q1-Q3)35 (22-51)Final outcomes, n (%) Persistently seronegative336 (94.4) Persistently seropositive6 (1.7) Seroreversion5 (1.4) Seroconversion3 (0.8) False seroconversion2 (0.6) Others4 (1.1)∗Connecticut, Pennsylvania, Texas, North Carolina, Virginia, Florida, Wisconsin, Delaware, New York, New Jersey.†Includes ZIP codes within NYC at or above 10 active tuberculosis cases/100,000 people.Table IIDemographics and outcomes of patients who seroconverted#SexAge (y)Zip code TB risk level∗Race and ethnicityTreatmentRisk factorsDuration of therapy prior to conversion (mo)Further management1M32LowWhite, not Hispanic, Latino, or Spanish originAdalimumabOpioid use disorder, IV drug use, exposure to tuberculosis through close contact, methotrexate use20Patient reported night sweats. Repeat QuantiFERON Gold test, AFB culture, CXR, and PPD were negative, no treatment for LTBI (FC)2M78LowWhite, declinedUstekinumabSmoking, T2DM12Treated with rifampin for 2 mo, discontinued due to abnormal LFT's3M71LowDeclinedAdalimumab, guselkumabNone known11 (adalimumab)1 (guselkumab)Repeat QuantiFERON Gold test was negative, patient continued guselkumab, no treatment for LTBI (FC)4F66LowWhite, not Hispanic, Latino, or Spanish originEtanercept, ustekinumabCrohn's disease, smoking24During etanercept treatment had positive QuantiFERON-TB Gold Plus, followed by normal CXR and 9 mo of INH. Four y after that, had 2 subsequent tests that were negative and positive, followed by 2 y of ustekinumab.5M75LowOther, not Hispanic, Latino, or Spanish originSecukinumabPositive PPD's 50 y ago, smoking, T2DM, hepatitis B, internal medicine physician with regular contact with immigrants as patient population6Treated with 9 mo of INHAFB, Acid-fast bacillus; CXR, chest x-ray; FC, False conversion; INH, isoniazid; IV, intravenous; LTBI, latent tuberculosis infection; PPD, purified protein derivative; TB, tuberculosis.∗Low zip code tuberculosis risk level indicates under 10 active tuberculosis cases per 100,000 people.

We found a low rate of seroconversion (<1%) in patient taking biologics for dermatologic conditions in NYC, which has relatively high TB prevalence. Seroconversion rates in our study were surprisingly similar to studies conducted in cities with lower TB burdens. A retrospective study of 570 psoriasis patients taking TNF alpha inhibitors (TNFIs) in Iowa City, Iowa (TB burden 1.5/100,000), reported only 1 (0.2%) true seroconverter.2 In another single-center retrospective study of 265 psoriasis patients on TNFI’s in Cleveland, Ohio (TB burden 1.3/100,000), only 1 patient (0.4%) seroconverted.3 Studies conducted in countries with higher-TB prevalence reported higher seroconversion rates. A retrospective study of psoriasis patients taking TNFI’s in Taipei, Taiwan (TB burden 30/100,000), reported 7.3% of patients seroconverting.4 In a retrospective study psoriasis patients taking TNFI’s in Ankara, Turkey (TB burden 16/100,000), 5.2% seroconverted.5

Limitations include small sample size, a single-center setting, and a retrospective design.

In sum, we found a low rate of seroconversion (<1%) in patient taking biologics for psoriasis and hidradenitis suppurativa in NYC, which has relatively high TB burden. True seroconverters were older, on average, than other subjects. We recommend a single baseline QFT test and annual testing only for patients age ≥66 taking biologics for dermatologic conditions, which may reduce costs and avoid unnecessary treatments.

Conflicts of interest

Dr Lipner has served as a consultant for Ortho-Dermatologics, Moberg Pharmaceuticals, Eli Lilly, and BelleTorus Corporation. Authors Katsiaunis, Conway, and D'Angelo have no conflicts of interest to declare.