Hydrochlorothiazide Use and Risk of Skin Cancer: A Population-Based Retrospective Cohort Study.

PURPOSE: Hydrochlorothiazide (HCTZ) exposure has been linked to increased skin cancer in Caucasian (white) populations, especially squamous cell carcinoma (SCC), but not basal cell carcinoma (BCC). This study aimed to evaluate and compare skin cancer risks associated with HCTZ- and other antihypertensives use. METHODS: This retrospective cohort study utilized Taiwan's National Health Insurance Research Database. We identified patients aged 20 years and older, newly receiving antihypertensive medications between 2004 and 2015. We calculated the medication possession ratio (MPR) for the first 2 years of treatment to determine patient eligibility and treatment classification, whereby only patients with MPR above 80% were included. These were subsequently categorized by the type of antihypertensives they received, namely HCTZ, other thiazide diuretics, non-thiazide diuretics or non-diuretic antihypertensives. Cox proportional hazards model was used to evaluate skin cancer risks, and these were then classified as SCC or BCC. RESULTS: Our study included 41 086, 27 402, 19 613, and 856 782 patients receiving HCTZ, other thiazide diuretics, non-thiazide diuretics, and non-diuretic antihypertensives, respectively. We found BCC risks were similar when comparing HCTZ with other thiazides (adjusted hazard ratio: 0.84; 95% CI: 0.54-1.33), non-thiazide diuretics (0.93; 0.51-1.67), and non-diuretic antihypertensives (0.91; 0.66-1.26). We observed a higher SCC risk in the HCTZ group, compared to other thiazides (1.24; 0.74-2.08), non-thiazide diuretics (1.32; 0.70-2.51), and non-diuretic antihypertensives (1.23; 0.87-1.73), although the confidence intervals (CIs) were wide and crossed the null. CONCLUSIONS: We concluded that skin cancer need not be of major concern to physicians when prescribing antihypertensives for an Asian population.

Predicting the Time to Relapse Following Withdrawal from Different Biologics in Patients with Psoriasis who Responded to Therapy: A 12-Year Multicenter Cohort Study.

BACKGROUND: For patients with psoriasis, discontinuation of biologics following remission has become more common in daily practice. OBJECTIVE: We aimed to identify predictors and construct a predictive model for time to relapse following withdrawal from biologics. METHODS: This 12-year, multicenter, observational cohort study was performed in six dermatology centers between February 2011 and February 2024. We identified biological treatment episodes in patients with moderate-to-severe psoriasis and included only treatment episodes in which a clinical response (≥ 50% reduction in Psoriasis Area and Severity Index score [PASI 50] from baseline) was achieved and the patient withdrew from biological therapy with a well-controlled status (PASI < 10 and ≥ 50% improvement in PASI from baseline). The primary outcome was time to relapse, which was defined as the period from the last biologic administration to relapse. An extended multivariate Cox proportional hazards analysis (Prentice-Williams-Peterson Gap time model) was used to predict relapse and generate a predictive model. RESULTS: This study screened 1613 biological treatment episodes, and 991 treatment episodes were enrolled. The time to relapse decreased significantly as the number of previous withdrawals from biological treatment increased (p < 0.001). Similarly, the time to relapse decreased significantly as the number of previous biologics used increased (p < 0.001). The maximum PASI improvement during biological treatment decreased and the PASI score at withdrawal of biological treatment increased in parallel as the number of prior withdrawals from biologics increased. The time to relapse following withdrawal was longest for interleukin (IL)-23 inhibitors (IL-23i), followed by the IL-12/23i, IL-17 inhibitors (IL-17i), and tumor necrosis factor-α inhibitors. After adjustment, multivariate Cox regression identified the following significant predictors of relapse following withdrawal: the mechanisms of action of biologics (hazard ratio [HR] for IL-17i vs IL-12/23i, 1.59; HR for IL-23i vs IL-12/23i, 0.60), number of previous withdrawals from biological treatment (HR 1.23; 95% confidence interval [CI] 1.13‒1.33), time to achieve PASI 50 (HR 1.01; 95% CI 1.00‒1.02), maximum PASI improvement on biologics (HR 0.98; 95% CI 0.98‒0.99), and PASI at the end of therapy (HR 1.03; 95% CI 1.01‒1.05). The model had good predictive and discriminative ability. CONCLUSIONS: These results have the potential to help physicians and patients make individualized treatment decisions; information on the risk of relapse of psoriasis at specific timepoints following the withdrawal of biologics is particularly valuable for patients considering discontinuation of biologics or as-needed biologic therapy. However, the benefit and risk of repeated withdrawals of biologics should be carefully weighed, as the treatment efficacy and duration of remission decline as the number of withdrawals increases.

Cataract Surgery and Incidence of Retinal Vascular Occlusion: Population-Based Cohort Study Using a Target Trial Emulation Framework.

BACKGROUND: Previous studies suggested an association between cataract surgery and retinal vascular occlusion. However, the association may be attributable to detection bias because postoperative monitoring may be more frequent for those who receive cataract surgery than for those who do not. DESIGN: Population-based cohort study using target trial emulation framework. METHODS: We included patients with cataract aged 50 years and older receiving cataract surgery or nonsurgical interventions identified from the Taiwan National Health Insurance Research Database between 2003 and 2018, matched by propensity score. The primary outcome was retinal vascular occlusion. Cox proportional hazards models were used to compare surgery and control groups. Additional analyses were restricted to patients who had undergone fundoscopic examination within 6 months prior to cataract surgery to address the issue of detection bias. RESULTS: We included 577,129 cataract surgery and control pairs. We found the hazard ratio (HR) for retinal vascular occlusion after cataract surgery was 1.23 (95% confidence interval (CI): 1.17-1.29), compared with the control group. Secondary outcome analyses yielded similar results for retinal artery occlusion (HR: 1.13, 95% CI: 1.02-1.26) and retinal vein occlusion (HR: 1.26, 95% CI: 1.20-1.33). However, no risk of retinal vascular occlusion was observed among patients who had received fundoscopic examinations (HR: 1.06, 95% CI: 0.98-1.15) at baseline. CONCLUSIONS: Our study underscored the importance of conducting complete baseline fundoscopic examinations before cataract surgery to clarify whether postoperative conditions are due to patients' underlying diseases or unintended complications of cataract surgery.

Risk of age-related macular degeneration in men receiving 5α-reductase inhibitors: a population-based cohort study.

BACKGROUND: Recent studies suggest that 5α-reductase inhibitors (5ARIs) for benign prostate hyperplasia (BPH) result in abnormal retinal anatomical alteration. OBJECTIVE: To compare age-related macular degeneration (AMD) incidence in BPH patients receiving 5ARIs or tamsulosin. DESIGN: Retrospective, population-based cohort study using new-user and active-comparator design. SETTING: General population. SUBJECTS: Males with BPH, newly receiving 5ARIs or tamsulosin from 2010 to 2018. METHODS: Data were extracted from Taiwan's National Health Insurance Research Database. We used Cox proportional hazards model with 1:4 propensity score (PS) matching, based on intention-to-treat analysis to determine the risk of incident AMD. Sensitivity analyses included an as-treated approach and weighting-based PS methods. We also separately reported the risks of incident AMD in patients receiving finasteride and dutasteride to determine risk differences among different 5ARIs. RESULTS: We included 13 586 5ARIs users (mean age: 69 years) and 54 344 tamsulosin users (mean age: 68.37 years). After a mean follow-up of 3.7 years, no differences were observed in the risk of incident AMD between 5ARIs and tamsulosin users [hazard ratio (HR): 1.06; 95% confidence intervals (95% CI): 0.98-1.15], with similar results from sensitivity analyses. However, increased risk of incident age-related macular degeneration was observed in patients receiving dutasteride [HR: 1.13; 95% CI: 1.02-1.25], but not in those receiving finasteride [HR: 0.99; 95% CI: 0.87-1.12], in the subgroup analyses. CONCLUSIONS: We found no difference between 5ARIs and tamsulosin regarding the incidence of AMD in BPH patients. However, the risk profiles for AMD differed slightly between dutasteride and finasteride, suggesting that the potency of androgen inhibition is a factor related to AMD incidence.

Comparative anatomical outcomes of high-flow vs. low-flow phacoemulsification cataract surgery: A systematic review and meta-analysis.

Background: Phacoemulsification is an effective and widely performed technique in cataract surgery, but the comparative anatomical outcomes, including endothelial cell loss (ECL), central corneal thickness (CCT), and central macular thickness (CMT), between high-flow and low-flow phacoemulsification cataract surgery remain unclear. Methods: This study followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. Random-effects models were applied to measure pooled mean differences (MD) with 95% confidence intervals (CI) of anatomical outcomes between high-flow and low-flow phacoemulsification cataract surgery. We judged overall certainty of evidence (CoE) based on Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria. Results: We included six randomized controlled trials (RCTs) totaling 477 participants. The meta-analysis showed similar changes associated with these two surgery types in both ECL at postoperative days 2-14 (MD: -1.63%; 95% CI: -3.73 to 0.47%; CoE: very low), days 15-42 (MD: -0.65%; 95% CI -2.96 to 1.65%; CoE: very low) and day 43 to month 18 (MD: -0.35%; 95% CI: -1.48 to 0.78%; CoE: very low), and CCT at postoperative day 1 (MD: -16.37 µm; 95% CI: -56.91 to 24.17 µm; CoE: very low), days 2-14 (MD: -10.92 µm; 95% CI: -30.00 to 8.16 µm; CoE: very low) and days 15-42 (MD: -2.76 µm; 95% CI: -5.75 to 0.24 µm; CoE: low). By contrast, low-flow phacoemulsification showed less increase in CMT at postoperative days 15-42 (MD, -4.58 µm; 95% CI: -6.3 to -2.86 µm; CoE: low). Conclusions: We found similar anatomical outcomes, except in CMT, for both high-flow and low-flow phacoemulsification cataract surgery. Future head-to-head RCTs on visual outcomes should confirm our findings. Systematic review registration: PROSPERO, identifier: CRD42022297036.

Comparison of Sodium-Glucose Cotransporter 2 Inhibitors vs Glucagonlike Peptide-1 Receptor Agonists and Incidence of Dry Eye Disease in Patients With Type 2 Diabetes in Taiwan.

Importance: Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been found to improve low-grade systemic and tissue inflammation; however, the association between SGLT2 inhibitor use and the incidence of dry eye disease (DED) has not been explored. Objective: To investigate the association between SGLT2 inhibitor use and dry eye disease in patients with type 2 diabetes (T2D). Design, Setting, and Participants: A retrospective cohort analysis of the largest multi-institutional electronic medical records database in Taiwan was conducted to identify patients with T2D newly receiving SGLT2 inhibitors or glucagonlike peptide-1 receptor agonists (GLP-1 RAs) from 2016 to 2018. Data analysis was performed from March 1 to May 31, 2022. Propensity scores with inverse probability of treatment weighting were generated to enable homogeneous comparisons between the 2 groups. Exposures: Treatment with SGLT2 inhibitors or GLP-1 RAs. Main Outcomes and Measures: Incident dry eye disease, which was defined by clinical diagnoses, plus the related drug prescription. Cox proportional hazards regression models were used to estimate hazard ratios with 95% CIs for the risk of DED. Results: A total of 10 038 and 1077 T2D patients newly receiving SGLT2 inhibitors (mean [SD] age, 59.5 [12.1] years; 5689 [56.7%] men) or GLP-1 RAs (mean [SD] age, 58.5 [41.2] years; 587 [54.5%] men), respectively, were included in the analysis. The incidence of DED was lower in patients newly receiving SGLT2 inhibitors (9.0 events per 1000 person-years) compared with those receiving GLP-1 RAs (11.5 events per 1000 person-years), yielding a hazard ratio of 0.78 (95% CI, 0.68-0.89). Subgroup analyses indicated that the lowered DED risks associated with SGLT2 inhibitors in patients with T2D were similar across different age, sex, blood glucose level, and kidney function groups. Results from the sensitivity analyses (including the propensity score-matching approach, on-treatment analyses, and different follow-up periods of 1, 2, and 3 years) were similar to the main analyses. Conclusions and Relevance: The findings of this study suggest that patients with T2D newly receiving SGLT2 inhibitors may have a lower risk for DED compared with those receiving GLP-1 RAs. Prospective studies are needed to analyze these results.

Rose Bengal-Mediated Photodynamic Therapy to Inhibit Candida albicans.

Invasive Candida albicans infection is a significant opportunistic fungal infection in humans because it is one of the most common colonizers of the gut, mouth, vagina, and skin. Despite the availability of antifungal medication, the mortality rate of invasive candidiasis remains ~50%. Unfortunately, the incidence of drug-resistant C. albicans is increasing globally. Antimicrobial photodynamic therapy (aPDT) may offer an alternative or adjuvant treatment to inhibit C. albicans biofilm formation and overcome drug resistance. Rose bengal (RB)-mediated aPDT has shown effective cell killing of bacteria and C. albicans. In this study, the efficacy of RB-aPDT on multidrug-resistant C. albicans is described. A homemade green light-emitting diode (LED) light source is designed to align with the center of a well of a 96-well plate. The yeasts were incubated in the wells with different concentrations of RB and illuminated with varying fluences of green light. The killing effects were analyzed by the plate dilution method. With an optimal combination of light and RB, 3-log growth inhibition was achieved. It was concluded that RB-aPDT might potentially inhibit drug-resistant C. albicans.

The Immunogenetics of Photodermatoses.

Photodermatosis is an abnormal skin inflammatory reaction to light. The major classifications of photodermatoses are idiopathic photodermatoses, photodermatoses due to exogenous or endogenous agents, photo-exacerbated dermatoses, and photosensitive genodermatoses. In this chapter, we focus on idiopathic photodermatoses and drug-related photodermatoses and emphasize on the epidemiology and immunogenetic backgrounds. Idiopathic photodermatoses, a spectrum of diseases with abnormal responses to ultraviolet radiation (UVR), include polymorphous light eruption, actinic prurigo, hydroa vacciniforme, chronic actinic dermatitis, and solar urticaria. Young people are more susceptible to most idiopathic photodermatoses except for chronic actinic dermatitis. Interestingly, idiopathic photodermatoses exhibit different characteristics between Caucasians and Asians. For example, the average age of Asian actinic prurigo patients is older than that of Caucasians in which genetic backgrounds or Fitzpatrick skin type might play a role. Drug-induced photodermatoses can be classified into phototoxic and photoallergic drug reactions. Certain drug-induced photodermatoses may mimic other dermatoses. For instance, drug-induced lupus erythematosus (LE) should be considered if an old man is diagnosed with LE but had a poor response to standard treatments.

The Immunogenetic Aspects of Photodynamic Therapy.

Photodynamic therapy (PDT) has become the first-line treatment of actinic keratosis, superficial basal cell carcinoma, and squamous cell carcinoma in situ (Bowen's disease) in dermatology. The off-label use of PDT has also escalated in recent years owing to its applications in the treatment of various non-neoplastic skin diseases such as acne vulgaris, vascular lesions, rejuvenation, and chronic wounds. Daylight PDT that uses natural sunlight to activate a photosensitizer with advantages such as low cost and reduced pain is widely used in Europe. This chapter reviews the applications and immunogenetic aspects of PDT. However, the studies of immunity and genetic changes in human tissue after PDT are limited.

Association between sodium glucose co-transporter 2 inhibitors and incident glaucoma in patients with type 2 diabetes: A multi-institutional cohort study in Taiwan.

PURPOSE: Type 2 diabetes (T2D) is an important risk factor for glaucoma, and sodium-glucose co-transporter 2 (SGLT2) inhibitors have been shown to protect the optic nerves. We therefore aimed to evaluate the association between SGLT2 inhibitors and incident glaucoma. METHODS: This retrospective cohort study analyzed the largest multi-institutional electronic medical records database in Taiwan, containing data of over a million individuals. We included T2D patients newly prescribed SGLT2 inhibitors or glucagon-like peptide-1 receptor agonists (GLP-1 RAs) from 2016 to 2018. Our primary outcome was incident glaucoma diagnosis between initiation of SGLT2 inhibitors or GLP-1 RAs, and 31st March 2021. After applying inverse probability of treatment weighting (IPTW) to increase homogeneity between the two treatment groups, we estimated hazard ratios (HR) with 95% confidence intervals (CI) for the risk of glaucoma, based on Cox proportional hazards regression models. RESULTS: We included 9,927 and 1,065 T2D patients who had been newly prescribed SGLT2 inhibitors or GLP-1 RAs, respectively. Lower risk of incident glaucoma was observed in patients receiving SGLT2 inhibitors (7.9 events per 1,000 person-years), compared to those receiving GLP-1 RAs (10.0 events per 1,000 person-years), with an HR of 0.81 (95% CI: 0.69-0.95). Multiple sensitivity analyses and a negative control outcome analysis confirmed the robustness of our main findings. CONCLUSION: This study suggests that T2D patients newly prescribed SGLT2 inhibitors have a reduced risk of incident glaucoma, compared to those prescribed GLP-1 RAs, in clinical practice. Future prospective studies are suggested to confirm this association.

Recent Advances in Photodynamic Therapy against Fungal Keratitis.

Fungal keratitis is a serious clinical infection on the cornea caused by fungi and is one of the leading causes of blindness in Asian countries. The treatment options are currently limited to a few antifungal agents. With the increasing incidence of drug-resistant infections, many patients fail to respond to antibiotics. Riboflavin-mediated corneal crosslinking (similar to photodynamic therapy (PDT)) for corneal ectasia was approved in the US in the early 2000s. Current evidence suggests that PDT could have the potential to inhibit fungal biofilm formation and overcome drug resistance by using riboflavin and rose bengal as photosensitizers. However, only a few clinical trials have been initiated in anti-fungal keratitis PDT treatment. Moreover, the removal of the corneal epithelium and repeated application of riboflavin and rose bengal are required to improve drug penetration before and during PDT. Thus, an improvement in trans-corneal drug delivery is mandatory for a successful and efficient treatment. In this article, we review the studies published to date using PDT against fungal keratitis and aim to enhance the understanding and awareness of this research area. The potential of modifying photosensitizers using nanotechnology to improve the efficacy of PDT on fungal keratitis is also briefly reviewed.

Risk of diabetic macular oedema with sodium-glucose cotransporter-2 inhibitors in type 2 diabetes patients: A multi-institutional cohort study in Taiwan.

AIMS: To investigate the risk of diabetic macular oedema (DMO) associated with the use of sodium-glucose cotransporter-2 (SGLT2) inhibitors in patients with type 2 diabetes mellitus (T2DM). MATERIALS AND METHODS: We conducted a retrospective cohort study by analysing a large multi-institutional electronic medical records database in Taiwan. We included adult patients with T2DM without DMO newly receiving either SGLT2 inhibitors or glucagon-like peptide-1 receptor agonists (GLP-1RAs) during the period 2016 to 2018. We used propensity scores with inverse probability of treatment weighting to generate comparable groups. The study outcome was incident DMO, determined by clinical diagnosis during outpatient visits or admissions. We followed patients from the index date to either DMO occurrence, last clinical visit, patient death, or December 31, 2020. We performed Cox proportional hazards regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk of DMO. RESULTS: We included 9986 new users of SGLT2 inhibitors (mean [SD] age 59.6 (12.1) years, median [interquartile range {IQR}] glycated haemoglobin [HbA1c] 70 (61-81)mmol/mol, estimated glomerular filtration rate [eGFR] 89.1 [71.4-108.7] mL/min/1.73 m2 and urine albumin-creatinine ratio [UACR] 26.1 [9.7-117.6] mg/g) and 1067 new users of GLP-1RAs (mean [SD] age 58.4 (41.5) years, median [IQR] HbA1c 73 [64-84] mmol/mol, eGFR 91.6 [68.6-114.0] mL/min/1.73 m2 and UACR 37.6 [11.1-153.2] mg/g) with similar baseline characteristics. Lower DMO risks were observed among patients newly receiving SGLT2 inhibitors (7.9/1000 person-years), compared to those receiving GLP-1RAs (10.7/1000 person-years) with an HR of 0.75 (95% CI 0.64-0.88). CONCLUSIONS: Our findings suggest use of SGLT2 inhibitors was associated with lower risk of DMO in T2DM patients in clinical practice, compared to use of GLP-1RAs. Future studies are necessary to confirm this observation.

Cutaneous cytomegalovirus (CMV) infection in a patient with metastasized lung cancer.

Diagnosing cutaneous cytomegalovirus (CMV) is difficult due to its rarity and diverse manifestations, and early recognition is crucial as it may indicate disseminated disease and a poor prognosis. We examined a 71-year-old Taiwanese male presenting with a 1-week history of progressive, painful papulopustules associated with superficial ulcers and thick yellowish crusts on the scalp. He had been diagnosed with stage IVb lung adenocarcinoma 6 weeks earlier, and the epidermal growth factor receptor inhibitor (EGFRI) erlotinib and radiotherapy had been started to treat brain metastases 1 month before he came to our clinic. Histopathological examination of a scalp lesion and ELISA and PCR testing of blood samples were indicative of disseminated CMV infection. Unfortunately, the patient passed away the day after his scalp biopsy, before the investigations confirmed the infection. We would like to highlight the importance of remaining vigilant for cutaneous CMV in end-stage cancer patients receiving tyrosine kinase inhibitors (TKIs) and recognizing how this potentially life-threatening viral infection can masquerade as a possible side effect of erlotinib.

Psoriasis in the geriatric population: A retrospective study in Asians.

There is a paucity of data focusing on geriatric psoriatic patients. The clinical features were different among those with early-onset psoriasis and elderly-onset psoriasis among the geriatric population. From 2014 to 2018, a total of 290 geriatric psoriatic patients were retrospectively enrolled in our study. They were subclassified into two groups, early-onset (aged <60 years, n = 154) and elderly-onset (aged ≥60 years, n = 136). The characteristics and treatment course of these two groups were reviewed. Psoriasis of the elderly-onset group was generally milder than the early-onset groups (P < 0.05). Less nail involvement and arthritis were noted among the elderly-onset group (P < 0.05). There were four cases of erythrodermic psoriasis in the early-onset group and three cases of palmoplantar psoriasis in the elderly-onset group. Oral medication and biologics for treatment of psoriasis appeared to be safe among the geriatric psoriatic patients. Elderly-onset psoriasis has features which are distinct from early-onset psoriasis and may be a particular subtype, which needs further evaluation.

Predictors of hepatitis B and C virus reactivation in patients with psoriasis treated with biologic agents: a 9-year multicenter cohort study.

BACKGROUND: The increasing use of biologics is accompanied by a risk of hepatitis B (HBV) and C virus (HCV) reactivation. OBJECTIVE: To determine the predictors of HBV and HCV reactivation in patients with psoriasis receiving biologics. METHODS: This study screened 2060 patients with psoriasis (3562 treatment episodes) who were taking biologics from 2009 to 2018. There were 359 patients with psoriasis with HBV (561 treatment episodes) and 61 with HCV infection (112 treatment episodes). RESULTS: During 8809 and 1522 person-months of follow-up, 88 treatment episodes for HBV involved HBV reactivation, and 14 episodes of HCV involved reactivation. The reactivation rate was significantly higher in treatment episodes of chronic HBV infection than in that of occult HBV (34.3% vs 3.2%, P = .001) and resolved HBV (34.3% vs 5.0%, P < .001). The multivariate analysis revealed that being hepatitis B surface antigen seropositive, being hepatitis B e-antigen seropositive, and tumor necrosis factor-α-inhibitor therapy were risk factors for HBV reactivation, whereas antiviral prophylaxis was effective in reducing the risk of HBV reactivation. No predictors were significantly associated with HCV reactivation. LIMITATIONS: Observational design and a lack of a comparison group. CONCLUSION: Patients with psoriasis on biologics have a risk of HBV and HCV reactivations, particularly those who are seropositive for hepatitis B surface antigen and hepatitis B e-antigen and undergoing tumor necrosis factor-α-inhibitor therapy.

Whole genome sequencing identifies genetic variants associated with co-trimoxazole hypersensitivity in Asians.

BACKGROUND: Co-trimoxazole, a sulfonamide antibiotic, is used to treat a variety of infections worldwide, and it remains a common first-line medicine for prophylaxis against Pneumocystis jiroveci pneumonia. However, it can cause severe cutaneous adverse reaction (SCAR), including Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reaction with eosinophilia and systemic symptoms. The pathomechanism of co-trimoxazole-induced SCAR remains unclear. OBJECTIVE: We aimed to investigate the genetic predisposition of co-trimoxazole-induced SCAR. METHODS: We conducted a multicountry case-control association study that included 151 patients with of co-trimoxazole-induced SCAR and 4631 population controls from Taiwan, Thailand, and Malaysia, as well as 138 tolerant controls from Taiwan. Whole-genome sequencing was performed for the patients and population controls from Taiwan; it further validated the results from Thailand and Malaysia. RESULTS: The whole-genome sequencing study (43 case patients vs 507 controls) discovered that the single-nucleotide polymorphism rs41554616, which is located between the HLA-B and MICA loci, had the strongest association with co-trimoxazole-induced SCAR (P = 8.2 × 10-9; odds ratio [OR] = 7.7). There were weak associations of variants in co-trimoxazole-related metabolizing enzymes (CYP2D6, GSTP1, GCLC, N-acetyltransferase [NAT2], and CYP2C8). A replication study using HLA genotyping revealed that HLA-B∗13:01 was strongly associated with co-trimoxazole-induced SCAR (the combined sample comprised 91 case patients vs 2545 controls [P = 7.2 × 10-21; OR = 8.7]). A strong HLA association was also observed in the case patients from Thailand (P = 3.2 × 10-5; OR = 3.6) and Malaysia (P = .002; OR = 12.8), respectively. A meta-analysis and phenotype stratification study further indicated a strong association between HLA-B∗13:01 and co-trimoxazole-induced drug reaction with eosinophilia and systemic symptoms (P = 4.2 × 10-23; OR = 40.1). CONCLUSION: This study identified HLA-B∗13:01 as an important genetic factor associated with co-trimoxazole-induced SCAR in Asians.