Nasal nitric oxide in post-acute COVID-19 cough: A comparison with chronic cough and the role of current allergic rhinitis

Post-acute COVID-19 cough (PACC) is a persistent or recurrent cough lasting >3 weeks after SARS-CoV-2 infection without other causes. This study examined nasal nitric oxide (nNO) in PACC patients to evaluate diagnostic and treatment potential. In this retrospective study, we enrolled 156 PACC patients after December 2022 and 161 chronic cough patients before December 2022. Compared to chronic cough patients, PACC patients had higher rates of current allergic rhinitis (60.9% vs 37.3%; P < .001), higher nNO levels (536 ± 192 ppb vs 483 ± 189 ppb; P = .014), and a greater proportion of elevated nNO (57.1% vs 42.9%; P = .012). Initial binary logistic regression indicated that both PACC (odds ratio [OR] = 1.771, 95% confidence interval [CI]: 1.135–2.764; P = .012) and current allergic rhinitis were associated with elevated nNO. However, multivariate logistic regression showed that only current allergic rhinitis remained an independent risk factor for elevated nNO (OR = 5.168, 95% CI: 3.121–8.558; P < .001), not PACC. Consistently, when comparing PACC patients without allergic rhinitis to chronic cough patients without it, no significant differences were found in nNO levels (436 ± 150 ppb vs 428 ± 179 ppb; P = .790) or elevated nNO rates (29.6% vs 29.3%; P = .971). The increased nNO observed in PACC patients compared to those with chronic cough is primarily driven by a higher concomitant prevalence of current allergic rhinitis in the PACC group, rather than by PACC itself.