Incidence and clinical patterns, severity and preventability of cutaneous adverse drug reactions among hospitalized patients in a tertiary centre.

INTRODUCTION: Cutaneous adverse drug reactions (cADRs) are among the most common manifestations of adverse drug reactions, ranging from mild eruptions to severe, lifethreatening conditions such as Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) and drug reaction with eosinophilia and systemic symptoms (DRESS). Despite increasing reports from Malaysia's National Pharmaceutical Regulatory Agency, local epidemiological data at the state level remain scarce. This study aimed to determine the incidence, clinical patterns, severity, and preventability of cADRs among hospitalized patients in Hospital Tuanku Ja'afar Seremban (HTJS), and to identify the drugs most frequently implicated and predictors of severe disease.

MATERIALS AND METHODS: We conducted a prospective, observational cross-sectional study over six months (February-July 2024) at HTJS. Patients admitted with, or developed cADRs during hospitalization secondary to systemic medications were included. Exclusion criteria were allergic/irritant contact dermatitis, chemotherapy-induced alopecia, allergic reactions to radiographic contrast or blood products, and outpatient cases. Data on demographics, clinical features, implicated drugs, severity (modified Hartwig and Siegel scale), preventability (Schumock and Thornton scale), and causality (Naranjo's Algorithm) were collected. Multiple logistic regression identified predictors of severe cADRs.

RESULTS: Among 30,667 admissions, 70 patients met inclusion criteria (incidence: 0.228%). The mean age was 46.2 ± 21.4 years; 55.7% were female and 71.4% Malay. Most cases occurred in medical departments (60%). The commonest reaction patterns were maculopapular eruption (37.1%) and urticaria (35.7%). Antibiotics accounted for 50% of cases, with penicillin being the leading culprit (37.1%), followed by NSAIDs, analgesics, anti-platelet and antituberculosis drugs. Most reactions were of moderate severity (80.0%); one SJS/TEN case was classified as severe according to Hartwig scale. Preventability assessment found 14.3% definitely preventable events, primarily due to re-exposure to known allergens. Multiple logistic regression identified raised eosinophil count (AOR 21.83, p=0.001), mucosal involvement (AOR 29.82, p=0.016), and impaired renal function (AOR 7.98, p=0.024) as independent predictors of severe reactions.

CONCLUSION: Our study highlights a cADR incidence of 0.228% among hospitalized patients, with antibiotics, especially penicillin group, being the most frequent culprit drug. While most reactions were moderate and not preventable, significant predictors of severity included raised eosinophils, mucosal involvement, and renal impairment. Enhanced vigilance, careful drug selection, and early recognition of high-risk clinical features are crucial to reducing the burden of cADRs in hospital settings.