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Analysis of changes and trends in the use of sedatives in dental sedation using data from the National Health Insurance in Korea

Background Although dental sedation helps control anxiety and pain, side effects and serious complications related to sedation are gradually increasing. Due to the introduction of new drugs and sedation methods, insurance rates, legal regulations, drugs, and methods used for dental sedation are inevitably changed. In the Republic of Korea, National Health Insurance is applied to all citizens, and this study investigated changes in the use of sedatives using this big data. Methods This study used customized health information data provided by the Healthcare Insurance Review & Assessment Service of Korea. Among patients with a record of use of at least one of eight types of sedatives for dental sedation between January 2007 and September 2019 were selected; the data of their overall insurance claims for dental treatment were then analyzed. Results The number of patients who received dental sedation was 786,003, and the number of dental sedation cases was 1,649,688. Inhalational sedation using nitrous oxide (N2O) accounted for 86.8% of all sedatives that could be claimed for drugs and treatment. In particular, it was confirmed that the number of requests for sedation using N2O sharply increased each year. Midazolam showed an increasing trend, and in the case of chloral hydrate, it gradually decreased. Conclusion According to our analysis, the use of N2O and midazolam gradually increased, while the use of chloral hydrate gradually decreased.


INTRODUCTION
Anxiety and phobia of dental treatment are common and important factors that negatively influence treatment outcomes. In 1987, Weinstein et al. [1] reported that 6-14% of the total US population had dental phobia, and in 1995, Klingberg et al. [2] reported that dental phobia caused a lower frequency of dental visits and consequently worsened oral health problems. In 2016, Appukuttan et al. [3] reported that avoidance of dental treatment due to dental phobia caused a vicious cycle of oral health problems. This shows the seriousness of the problem of dental phobia from the past to the present.
Dental sedation helps improve treatment outcomes by controlling anxiety and fear [4,5]. As awareness of the importance of satisfaction with dental treatment increases, the number of sedation cases in dental treatment also increases [6].
Sedation was mainly used for children and patients with disability in the Republic of Korea, but its use has been steadily increasing in recent years due to changes in the medical insurance system, such as the insurance application of nitrous oxide (N 2 O) [6]. According to a 2012 survey on dental sedation in the Republic of Korea, chloral hydrate, hydroxyzine, and midazolam were mainly used as oral sedatives, and midazolam and propofol were used as intravenous sedatives. N 2 O was used as an inhalational sedative [7].
However, in the Republic of Korea, misuse of propofol and deaths due to deep sedation using chloral hydrate or sevoflurane in children have led to social problems. Therefore, with the enactment of the sedation guidelines by the Korean Dental Association (KDA), the use of this drug in dental sedation has not been recommended [8].
In the Republic of Korea, the National Health Insurance system was implemented as company medical insurance and regional insurance were integrated on July 1, 1989, and most Koreans (97.2%, as of April 2020) were enrolled in the National Health Insurance. Accordingly, all medical institutions providing medical care under the insurance had to fill in the records of medical treatment and medications performed on the medical expense claim statement and submit it to the Korean National Health Insurance Service (NHIS) [9]. The NIHS and the Health Insurance Review & Assessment (HIRA) Service secure data such as the medical history of all patients who received insurance treatment, disease codes, and claim codes. The accumulated insurance treatment information for all citizens is coded and provided by the HIRA in the form of big data, and many researchers are trying to obtain new results by analyzing it in various ways [10].
In this study, using big data for health and medical care, the trends related to the types of drugs used in dental sedation were investigated, and the characteristics of sedation by year and age were analyzed.
The data analyzed in this study reflect the current dental sedation situation and can be used as reference for future KDA and national dental policy establishment, as well as in dental educational institutions.

Study design and population
This study received approval from the institutional review board of our institution (No. S-D20200006). The analysis data used in the study were customized health information data from the HIRA (approval No.

M20191014119).
First, the payment data of patients at dental hospitals and dental clinics of eight types of representative drugs (chloral hydrate, hydroxyzine, midazolam, triazolam, propofol, sevoflurane, N 2 O, and dexmedetomidine) that can be used for dental sedation were requested from the Healthcare Bigdata Hub (HBH) of HIRA. In addition, we requested all insurance claims data of patients who underwent dental sedation for additional analysis [11].    (300   table) on the same date, it was classified as a case of combined use.

Trends in sedation drug use by date and year
The numbers of claims per day and year for each sedative drug were analyzed. Using the pseudonym personal identification number (JID), we analyzed the number of sedation cases performed on the same patient.
The number of medical institutions that performed sedation was also analyzed using the pseudonym hospital identification number (YID). The age and sex of each sedative drug were analyzed.

Analysis of the sedation duration and number of trials of sedation in a patient
There are three N 2 O behavioral management codes: U2370, U2371, and U2372. U2370 is the basic code for 15 min when first executed, U2371 is a code added every 15 min, and U2372 is the code for 30 min after 1 h. If we count the number of these codes, we can roughly calculate the duration of sedation execution. Calculation of the duration of sedation using this code is only possible with sedation cases that have been executed, including N 2 O.

RESULTS
Trend of sedative use for dental sedation in Korea http://www.jdapm.org 53         difficult to re-analyze the U2370 data from the HIRA data hub again because of various limitations.

Changes in the number of sedatives used by year
In the case of sedation with chloral hydrate alone and sedation with chloral hydrate (except midazolam mixed), the number of cases has been gradually decreasing since the mid-2010s (Fig. 3, Table 3). Other drugs also showed an increasing trend and then gradually decreased, but the cases of N 2 O alone and mixed use of N 2 O and midazolam continuously increased (Fig. 3).
The proportion of propofol used is very low compared to other drugs, because insurance claims are often impossible in the Republic of Korea for propofol sedation, and it is thought that a large proportion of dental sedation cases with propofol in adults are prescribed without insurance. Table 4 shows the number of dental clinics or dental hospitals that make insurance claims for dental sedative drugs, which is increasing every year.

Analysis of sedation use by age
According to the annual change in the average age of  patients who underwent sedation, there was no significant change in other drugs, but an increase was observed in the case of N 2 O inhalation sedation. In the case of N 2 O, the highest age ratio in 2015 was 4 years, but it increased to 5 years in 2017, and in 2019, according to the statistics up to September, the age increased to 8-15 (Fig. 4). On the other hand, in the case of combined use of N 2 O, chloral hydrate, and hydroxyzine, the proportion of those aged 3 and 4 did not change and occupied a high proportion regardless of the change in year (Fig. 5). In the case of the combination of N 2 O and midazolam, drugs with increased use, a high proportion was observed in ages 3-5 years old (Fig. 6).  (Fig. 7).

Analysis of the sedation duration and number of sedation trials in a patient
If we analyze the number of times a patient undergoes sedation by year, it can be seen that the number of cases that are administered more than twice increases (Fig. 8).  (Table 3), sedatives were administered in < 0.5% of all insured dental cases. The health and medical big data used in this study are the most extensive data in the Republic of Korea in terms of claimable treatment. Data from the National Health Insurance, to which > 97% of Koreans are enrolled, are highly reliable [12]. However, in the Republic of Korea, many dental treatments are performed without insurance claims, and a database has not been established to date to check sedative use data that are not covered by insurance. There is no way to check the number of sedation parts not covered by insurance.
The important point that could be confirmed through this study is the changing trend in the use of N 2 O inhalation sedation. In 2014, Yang et al. [13] published a survey on the use of sedation by pediatric dentists, and Choi et al. [14] in 1999 reported that 29% of pediatric dentists use sedation. In 2005, An et al. [15] reported that 66% of pediatric dentists use sedation, and in 2021, Tak et al. reported [16] that 89.5% of pediatric patients received sedation in dental treatment. An increase in the use of sedation compared to the past can be inferred, which can be directly confirmed statistically.
According to a survey on changes in the sedation environment in pediatric dental care in the United States for 25 years published by Houpt in 2010, the number of dentists who reported that the frequency of sedation used increased over the past 5 years increased, and 22% and 70% of dentists stated that the reason for the increased use of sedation was a change in the perception that more patients needed sedation [17].  [18].
Another factor that is increasing the use of N 2 O inhaled sedatives is increased emissions by pediatric dentists.
Unlike other subject matter experts, pediatric dentists receive specialized training in N 2 O inhalation sedation. This is because N 2 O inhalation sedation is more likely to be used than other sedation methods when opening the hospital after training (Table 4).
Contrary to the case of N 2 O inhalation sedation, chloral hydrate showed a marked decrease starting from 2014.
Chloral hydrate is an oral sedative clinically used since 1890, but has been used without approval from the US Food and Drug Administration and has consistently presented safety issues such as cardiotoxicity issues caused by overuse [19,20].

Since 2012, pharmaceutical companies in the United
States have stopped producing chloral hydrate. Accordingly, Han et al. [21] argued that chloral hydrate, which does not exist as an antagonist and cannot titrate the depth of oral sedation, needs to be considered as an alternative to other safer drugs for patient safety. As for the trend of decreasing chloral hydrate through this big data analysis, Lee et al. [22] reported that the rate of N 2  Conversely, the incidence of death due to sedation can be considered a factor in reducing the inflow of dental patients. A typical accident is the death of a 30-month-old girl in Cheonan, Chungcheongnam-do, on October 20, 2017, during dental sedation (SBS, 2017.10.23, https://news.sbs.co.kr/news). The frequency of use of inhalation sedation with sevoflurane, which had shown an increase in use before, rapidly decreased from 2017 (Table 3).
Changes in the age of patients receiving sedation are also noteworthy. In the case of N 2 O inhalation sedation, it was confirmed that the age of patients receiving sedation increased from 4 to 8-15 years old. Sedation should be applied with caution as the age of the child and poor systemic condition such as low body weight increase the onset of drug response faster, last longer, and increase the risk of deep sedation [20].
According to the age distribution of sedative drugs, N 2 O inhalation sedation and the use of various mixed drugs of N 2 O, chloral hydrate, midazolam, and hydroxyzine were mainly used in patients with an average age of ≤ 15 years. This tends to coincide with the drugs used in pediatric dentistry [15].
The duration of inhalational sedation by N 2 O alone is decreasing, and dental treatment does not end with one sedation, but increases to two or three times. Given the shortened sedation duration, compared to the past, when many dental treatments were performed with one sedation, the amount of dental treatment performed at one time has been reduced, the sedation duration is shortened, and dental treatment is performed by dividing it into several sedation sessions.
Despite the growing demand for dental sedation, the number of dental clinics offering sedation is not increasing rapidly, so the number of cases of sedation performed by one dental clinic is increasing. The reasons for the slow increase in the number of dental clinics performing sedation compared to the increase in the number of sedatives are the limited opportunities to learn dental sedation methods, the burden of purchasing equipment and drugs, and the heavy burden of bearing in case of a medical accident.
In conclusion, N 2 O and midazolam, which are sedative drugs that show an increasing pattern of use, are characterized by rapid onset, short recovery time, and low risk of complications such as respiratory problems [23].