DISCUSSION
Our study is the first multicentre study which has evaluated adherence to SCIT with aeroallergens during the COVID-19 pandemic and its influence on the short-term clinical outcomes in real-life. We observed that in half of the patients (53.8%), SCIT injections were delayed and one third (31.8%) of the patients were non-adherent during COVID-19 pandemic. Delays in SCIT administration have led to deterioration in the AIT effectiveness and QoL, and the deterioration was even greater in the non-adherent patients.
Adherence to long-term treatments in chronic diseases is very crucial for the success of the treatment3. The definition of adherence to SCIT differs in studies, however we referred to a previous study which was conducted by our group and considered the cut-off time interval for being non-adherent as 2 months accordingly2. Moreover, we also determined the clinical results of shorter delays of less than 2 months in injection intervals in a separate patient group in order to strengthen our findings. By this way, we have captured all significant clinical consequences of delays in injection intervals. Since our study is the first adherence study during the pandemic, we could only compare our results with previous SCIT adherence studies published before the pandemic. In the majority of the adherence studies on SCIT, the adherence rates are less than 70%2,10-13. Furthermore, they are even lower according to real-life data2,14,15. In our study, 68.2% of the patients were adherent to SCIT during the pandemic. We can speculate that this acceptable adherence rate in our study may be due to continuous treatment with appropriate preventive measures applied despite the negative effects of the pandemic and the close cooperation that had been established between the allergists and the patients in the study centres before the pandemic.
As a main finding of our study, delay in SCIT administrations led to deterioration in AR symptoms and QoL of our patients. Delays of less than 2 months between subsequent SCIT injections worsened QoL and symptom scores in Group 2 patients whereas in the non-adherent group MSs were additionally disrupted. Therefore, we suggest that it is important to continue SCIT injections without giving intervals more than recommended in order not to affect the short-term effectiveness of AIT even during a pandemic16. Prolonged intervals in the SCIT applications is also an important issue to make appropriate dose adjustments to restart SCIT after gaps in the administration17. In our study, after interruptions of maintenance doses especially in non-adherent patients, dose adjustments starting with frequent lower dose injections caused frequent hospital visits which can probably bring additional burden on the healthcare system.
The two main reasons of non-adherence to SCIT in our study were using public transport for reaching the hospital and receiving SCIT with HDMs. In accordance with our findings, a study from the USA reported that one of the reasons of premature cessation of SCIT was the inconvenience of travel18. It is very obvious that patients using public transportation during a pandemic may discontinue SCIT injection visits in order to reduce the risk of being infected. In a study, adherence to pollen SCIT was higher than the SCITs with other allergens14 while in other studies no relationship between allergen type and adherence was observed2,18. Since our study was conducted in the pollen season19,20, the adherence in patients receiving pollen SCIT was better than those receiving SCIT with HDMs. We assume that these patients were worried about having severe AR and/or asthmatic symptoms during the pollen season corresponding to the pandemic therefore received more regular SCIT injections. However, we did not observe any significant changes in the scores of the patients who received pollen or HDM SCIT before and during the pandemic. Moreover, VAS-symptom, VAS-QoL, TSS-6 and MS did not deteriorate during pollen season for most of the pollen SCIT patients who received the treatment regularly.
Among demographic factors; age, gender, occupation and socioeconomic status were related to non-adherence to SCIT in recent studies2,14,18,21,22. However, we did not observe any association between these factors and adherence. This difference might be due to the fact that the COVID-19 pandemic has similarly affected people with different demographic characteristics. Furthermore, having diagnosis of AR or AR with asthma was not related to adherence to SCIT administrations similar to some adherence studies2,12,23.
Our study focused on the effects of patient behaviours on SCIT application during the pandemic since the physician behaviours were not significantly different from the pre-pandemic period. However, the delay in SCIT applications may also occur due to the clinical practice preferences of the physicians. In a current international EAACI survey study investigating the AIT practice behaviours of physicians during the pandemic, it has been shown that 41% of the participants extended the application period and 13% paused it during the pandemic24. We believe our study is important in showing the short-term clinical consequences in case of delays between SCIT injections depending on patient behaviours and it also supports the recent AIT recommendations of EAACI1.
As a limitation of our study, we have compared our findings with results of previous adherence studies conducted during normal life while interpreting the clinical results of treatment disruptions related to the pandemic. However, social restrictions affecting different aspects of daily life and mental changes caused by the pandemic may generate its own dynamics which may limit the comparison of study results with previous studies. In addition, whereas adherence studies usually comprise of long periods of AIT, our study has presented adherence to SCIT for a short-term period of 6 months. However, we plan to further evaluate the same patient groups for longer periods to show long-term effectiveness of SCIT and adherence rates in relation to the pandemic. Finally, our results are convincing, regarding the high number of patients, similar median duration of maintenance phases of SCIT before the study between the groups and similar initial symptom, medication and quality of life scores, although the patient groups were not homogenous in terms of allergens applied during the SCIT injections, sensitivity and the presence of asthma.
In conclusion, in the current study, the negative effects of COVID-19 pandemic on adherence to SCIT administrations and short-term clinical efficacy have been demonstrated in real-life. We believe that it is important to continue SCIT administrations by providing the necessary precautions in allergy clinics during a pandemic in order to maintain the clinical efficacy of the treatment.