In this study, the trends and patterns of medication prescriptions for patients with AR were analyzed for the period from 2010 to 2018. The results confirmed that the prescription of antihistamines, particularly first-generation antihistamines, decreased while the prescription of steroids and LTRAs increased. The prescriptions of “antihistamines only” decreased, whereas the prescription rate of “antihistamine and nasal steroids” and “nasal steroids only” increased. However, the trends differed depending on patient characteristics. In particular, the increase in the rate of steroid prescription was relatively low in patients aged 0–5 years and ≥ 65 years. Furthermore, for these age groups, the rate of steroid prescription was also relatively low in combination prescriptions and first-choice prescriptions.
Some results of this study are consistent with a previously conducted survey in Korea. Antihistamines were the first-choice medication. Furthermore, pediatricians have reported lower prescription rates of combinations of antihistamines and nasal steroids and higher prescription rates of LTRAs than the prescription rates reported by physicians of other specialties . This trend was also confirmed in a subgroup analysis of our study. However, the previous study showed that the combination of nasal steroids and antihistamines was the most prescribed. By contrast, in the present study, the prescription rate of second-generation antihistamines alone was the highest, although it showed a decreasing trend. This variance may be attributed to difference in study subjects. In the present study, medical records of all relevant patients were analyzed, and thus, patients with mild AR were also included in the analysis. By contrast, as the previous study performed a survey that relied upon the physician’s memory, only prescription patterns for patients with frequent visits may have been reported.
In particular, a remarkable decrease was noted in the prescription rate of first-generation antihistamines, which could be attributed to the superiority of second-generation antihistamines. The latter have a faster and longer-lasting effect than the first-generation antihistamines , and are safer with only a slight sedative effect . Furthermore, second-generation antihistamines have been reported to be safer than first-generation antihistamines even when used in combination with other drugs . Also, ARIA and standard guidelines of the Korean Academy of Asthma, Allergy, and Clinical Immunology recommend the use of second-generation antihistamines [8, 9].
The use of nasal steroids has been increasing. Moreover, the combination of nasal steroids and antihistamines has shown the largest rate of prescription increase. ARIA and the standard guidelines of the Korean Academy of Asthma, Allergy, and Clinical Immunology state that nasal steroids are more effective than antihistamines in relieving nasal blockage [8, 9]. These results, and changes in the guidelines, are thought to have had some effect on the prescription patterns. However, compared with the extensive use of nasal steroids in other countries [11, 12], the use of nasal steroids in Korea has remained at around 10–20 %.
Rather, it should be noted that the use of systemic steroids was the highest among steroids in Korea, and the use of systemic steroids has shown an increasing trend. Prescription rates for systemic steroids were also the highest for the age groups 0–5 years and ≥ 65 years. Systemic steroids are only recommended for patients with very severe and therapy-resistant symptoms due to concerns of adverse events . This pattern was not identified in other countries [11, 12], and was not reported in the previous survey in Korea . Further studies are required to investigate the characteristics and prognosis of patients prescribed these drugs.
We observed increased prescription of LTRAs. These drugs alleviate nasal and ocular symptoms  and are more effective in combination therapy with antihistamines and steroids [23,24,25]. In particular, the safety of LTRAs demonstrated in children [26, 27] may have resulted in the increased prescription of LTRAs in patients aged 0–5 years. Based on these results, the reimbursement criteria for LTRAs were expanded in Korea at the end of 2017. Before the amendment, reimbursement was only possible when there was no improvement with antihistamine treatment, but now LTRAs are reimbursed even when prescribed as a first-line treatment . The increase in LTRAs prescriptions in 2018 is thought to have reflected these changes.
The prescription rates for allergic asthma and atopic dermatitis patients were similar to the total allergic rhinitis patients, except that the prescription rate of LTRAs was higher for allergic asthma and atopic dermatitis patients. LTRAs are effective for controlling asthma symptoms . Therefore, physicians might have prescribed the LTRAs for allergic rhinitis patients with asthma symptoms. Although the evidence of using LTRAs for atopic dermatitis is limited , the high prescription rates might be due to the younger age of atopic dermatitis patients (data not presented). The prescription rates of other medications should be interpreted with caution. Depending on patient’s severity, other medications, especially steroids, might have been prescribed with allergic asthma or atopic dermatitis as primary diagnosis, not allergic rhinitis. If the patient had been prescribed steroids with allergic asthma or atopic dermatitis as primary diagnosis closely before the patient visited for allergic rhinitis, the physicians might have not prescribed the steroids. Considering this, the actual prescription rates of steroids might be higher than observed.
Our study has limitations for generalization . First, this study analyzed insurance-covered medications prescribed in clinical practice, therefore non-covered medications were not included in the analysis. In particular, xylometazoline hydrochloride, the topical decongestant with the highest sales, could not be analyzed in this study because it is a non-reimbursable medicine. Accordingly, for decongestants, only systemic decongestants were investigated, and in this regard, generalizability is a drawback of this study. Also, we did not investigate antihistamines and topical decongestants sold as OTC preparations. This does not serve as a bias because this study aimed to investigate only the prescriptions of the clinicians. However, as OTC preparations are thought to have affected the prescription trend, the exact description of the factors related to the prescription trend remains a limitation. Further, allergen immunotherapy is a treatment emphasized in the guidelines and needs to be analyzed. However, since it is not covered by the national health insurance of South Korea, it could not be included in this study. In addition, there was a bias in the episode analysis of patients because yearly cross-sectional data were used. In particular, when analyzing first-choice prescriptions, if the patient’s prescription continued from the previous year, the prescription information of the previous year was not considered.
Nevertheless, to the best of our knowledge, the present study is significant because it is the first most extensive analysis on the long-term trends of medication prescriptions to treat AR. Furthermore, actual clinical decisions were analyzed from various perspectives with an analysis of a range of medication prescriptions and patterns. In particular, nationwide data representing the South Korean population were used, and all citizens and medical institutions are members of the Korean health insurance system as a regulatory requirement. Thus, the data were highly representative, and there were few limitations pertaining to the generalization of the study findings. Since there have been few analyses of AR prescription trends, the results of this study can be used to develop a clinical guideline in the future and can help confirm whether the guideline developed is clinically applicable.