Factors Influencing Treatment Adherence in Chronic Spontaneous Urticaria: A Systematic Review.

Chronic spontaneous urticaria (CSU) is characterized by recurrent wheals and/or angioedema without an identifiable trigger. Despite advances in therapy-including biologics such as omalizumab-suboptimal treatment adherence remains a major challenge, often resulting in poor symptom control and diminished quality of life. The objective of this study is to evaluate the existing literature on adherence in CSU and identify evidence-based strategies for improving long-term treatment engagement. A systematic literature search of PubMed and EMBASE was performed for articles published between 2000 and 2024 using the terms "chronic spontaneous urticaria," "chronic urticaria," "chronic idiopathic urticaria," "compliance," and "adherence." Eligible studies reported original data on adherence-related factors in CSU. Each study was categorized to World Health Organization (WHO) adherence dimensions: social/economic, healthcare system, condition-related, therapy-related, and patient-related. Risk of bias assessment was conducted for each study included in the final selection. The search followed PRISMA guidelines, and the protocol was registered with PROSPERO (ID: CRD42024627967). Twenty-one studies (totaling 18,500 patients) met inclusion criteria. Common barriers included lack of preventative medication use, inconvenience, forgetfulness, dissatisfaction with healthcare providers, and logistical challenges in accessing in-office biologic administration. Patients previously treated with immunosuppressants had a poorer response to omalizumab, which may contribute to nonadherence due to perceived lack of efficacy. External factors such as the COVID-19 pandemic also contributed to nonadherence by reducing clinic visits and access to specialist referrals. Higher education level and employment were significantly associated with improved adherence. Proposed strategies include simplifying treatment regimens, enhancing patient education about CSU chronicity, providing telehealth or home medication administration options, and offering financial or social support programs. Multiple interrelated barriers contribute to treatment nonadherence in patients with CSU, underscoring the need for multifaceted, patient-centered interventions. Clear communication, simplified regimens, and supportive resources may enhance adherence and help achieve improved long-term clinical outcomes.