We present our experience using dupilumab for the treatment of CRSwNP in the first year since it was approved in Canada for this indication. Improvement in the SNOT-22 scores seen in our cohort after 28 weeks (mean SNOT-22 = 23.47 SD 17.66; mean score change from baseline = − 32.85 SD 21.10) of therapy exceeded the minimal clinically important difference of 8.9 points. These changes were also seen in the efficacy of dupilumab in clinical trials (SNOT-22 score at 24 weeks for the treatment group in the SINUS-52 study was 23.84, with a least squares mean change from baseline of − 27.77) [5] and although a direct comparison cannot be made due to our small sample size, the results in our cohort show that similar clinical patient reported symptom improvement may be achieved outside of the controlled environment of clinical trials.

In the last 12 months at our centre, 85 patients applied for insurance coverage for dupilumab therapy, 42 patients (49%) received coverage and started therapy; one additional patient was denied coverage but started therapy by paying out of pocket. The main reason given by the insurers was that they were not considering coverage for the CRSwNP indication at the time of application. To date, the Canadian Agency for Drugs and Technologies in Health (CADTH) has provided a reimbursement recommendation for dupilumab for the atopic dermatitis and asthma indications [9, 10], however a reimbursement review has not been completed for the CRSwNP indication.

This study sought to identify evidence, from a single center tertiary care rhinology practice, of an efficacy-effectiveness gap between clinical trial results with dupilumab in comparison to real world experience. Baseline mean SNOT-22 score of the practice cohort (60.56, SD 21.63) exceeded the MCID when compared to the baseline data of the dupilumab trial groups (50.94, SD 20.66). However, the 24-week SNOT-22 scores (23.89, SD 18.77) from the treatment group in the SINUS-52 clinical trial were not different than similar time SNOT-22 scores of this clinical cohort (23.36 SD 15.97). This suggests that there does not appear to be an efficacy-effectiveness gap when considering symptom improvement as reported by patients using the SNOT-22 questionnaire. We were unable to evaluate other outcomes included in the SINUS- 24 and SINUS 52 studies such as polyp score, olfactory function using objective measures and Lund-Mackay CT scores, however, the SNOT-22 is a well validated instrument that is able to discern treatment effects and is representative of patient CRS-related quality of life. Further, the SNOT-22, a subjective patient reported outcome measure (PROM), has been identified as a key CRS outcome for research and currently the most notable when considering patient preference and value judgements for treatment options [11, 12]. As a yet even greater range of patients are prescribed dupilumab therapy, an efficacy-effectiveness gap could become evident due to factors such as comorbidities, compliance with both dupilumab and baseline medical therapy, and the severity of the disease, amongst other factors.

The Canadian Rhinology Working Group recommends that biologic therapies for chronic rhinosinusitis be considered only for patients who have failed medical therapy and have undergone sufficient sinus surgery or for patients who cannot undergo sinus surgery and have failed medical therapy [6]. However, at this time, access to dupilumab for Canadian patients and specifically in the province of Ontario, remains limited to only a fraction of those with private insurance. Currently, patients without private insurance have few options for attaining treatment with any monoclonal antibody therapy. For most patients, the therapy is cost prohibitive with only one patient from the current study having the means to self-fund therapy.

Long-term follow-up data is needed in order to determine if the higher yearly cost of dupilumab therapy is offset by the need for multiple surgeries, disease complications, the costs and any adverse effects of systemic and topical corticosteroids as well as the impact on the quality of life for patients who have poorly controlled CRSwNP. Underappreciated, is the effect of CRSwNP on the olfactory ability of patients, with those affected having levels of impact ranging from impairment, to disability and potential handicap [13]. In particular, the economic burden due to the sensory disability and, for some patients, the resultant handicap from olfactory loss has yet to be fully evaluated. Furthermore, anosmia presents a major safety issue for the anosmic individual and any of their dependents. CRSwNP patients treated with dupilumab experience improvement in their olfactory function [5]. In the present study this improvement was evidenced by a decrease in the SNOT-22 smell/taste score, however, the long-term effects of dupilumab on olfactory function require further study.