Increased respiratory viral detection and symptom burden among patients with primary antibody deficiency: results from the BIPAD study.

Abstract Background Patients with primary antibody deficiency (PAD) are at increased risk of respiratory tract infections but our understanding of their nature and consequences remains limited. Objective To define the symptomatic and microbial burden of upper airway infection in adults with PAD relative to age-matched controls. Methods Prospective 12-month observational study consisting of a daily upper and lower airway symptom score alongside fortnightly nasal swab with molecular detection of 19 pathogen targets. Results 44 patients and 42 controls (including 34 household pairs) were recruited, providing over 22,500 days of symptom scores and 1,496 nasal swabs. Swab and questionnaire compliance exceeded 70%. At enrolment, 64% of patients received prophylactic antibiotics with a 34% prevalence of bronchiectasis. On average, PAD patients experienced symptomatic respiratory exacerbations every 6 days compared to 6 weeks for controls, associated with significant impairment of respiratory-specific quality of life scores. Viral detections were associated with worsening of symptom scores from a participant’s baseline. PAD patients had increased odds ratio (OR) for pathogen detection, particularly viral (OR 2.73; 95% CI: 2.09 to 3.57), specifically human rhinovirus HRV (OR 3.60; 2.53-5.13), and parainfluenza (OR 3.06; 1.25-7.50). H. influenzae and S. pneumonia were also more frequent in PAD. Young child exposure, IgM deficiency, and presence of bronchiectasis were independent risk factors for viral detection. Prophylactic antibiotic use was associated with a lower risk of bacterial detection by PCR. Conclusion PAD patients have a significant respiratory symptom burden associated with increased viral infection frequency despite immunoglobulin replacement and prophylactic antibiotic use. This highlights a clear need for future therapeutic trials in the PAD-population, and informs future study design.