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INTRODUCTION
According to official statistics, over 10,000 individuals have died by suicide annually in Korea since the early 2000s.1 This places the country’s suicide rate among the highest in the Organization for Economic Cooperation and Development countries.2 In response, the Korean government has implemented suicide prevention policies since 2004, aiming to reduce the suicide rate and eliminate the stigma associated with having the highest suicide rate.3 The suicide rate in Korea peaked in 2011 at 31.7/100,000 and has been gradually declining since then.4 However, the rate has remained around 25/100,000 in the 2020s.1
Suicide prevention policies in Korea have been revised and implemented as five-year plans during the early years of each new government.5 These include the first (2004–2008), second (2009–2013), and third (2016–2020) Master Plans for Suicide Prevention (MPSP), the National Action Plan for Suicide Prevention (NAPSP) (2018–2022), and the currently implemented fifth MPSP (2023–2027).6 These suicide prevention policies have largely built upon previous initiatives, strengthening specific programs or expanding their scope.7 While these policies have included both selective high-risk and universal social approaches to suicide prevention, the primary strategy has been the expansion of mental health screening and early detection of suicide risk through lifeguard training and early referral to counseling or psychiatric treatment.8
Despite the downward trend in suicides in Korea since the implementation of the second MPSP, the government’s suicide prevention policies have consistently fallen short of their goals to reduce suicide rates (Table 1).6 Within a socio-economic and cultural context, the current suicide rate is largely determined by previous suicide trends.9 However, Korea’s suicide prevention policies may have set overly ambitious targets for reducing suicide rates.8 Upon examining recent policy cases, the NAPSP aimed to reduce the suicide rate from 25.6/100,000 in 2016 to 17.0/100,000 by 2022.10 However, the actual rate in 2022 was 25.2/100,000. The subsequent fifth MPSP also set a goal of reducing the suicide rate by 30%, from 26/100,000 in 2021 to 18.2/100,000 by 2027.1112 These challenging policy targets may reflect the political determination to reduce suicide. However, there have been criticisms regarding the lack of objective evidence in setting policy targets for suicide reduction, suggesting that the Korean government may be underestimating the deeply entrenched issue of suicide in society.8
Table 1
Historical suicide prevention policies in Korea
This study aimed to assess the practicability of the Korean government’s goal of reducing the suicide rate through its suicide prevention policies. We focused on the two most recent policies: the NAPSP (2018–2022) and the fifth MPSP (2023–2027). Our analyses were primarily conducted under two hypotheses. The first hypothesis was that the suicide trend observed during the NAPSP would continue into the period of the fifth MPSP. The second hypothesis was that the fifth MPSP could further decrease the suicide rate beyond the underlying trend, mirroring the effectiveness of the NAPSP. To evaluate the feasibility of achieving the ongoing fifth MPSP’s goal, we employed the following approach. First, we estimated the suicide reduction effect of the NAPSP by calculating the difference between the expected and actual suicide rates from 2018 to 2022. Next, we used monthly suicide rate data from 2011 to 2022 to forecast future suicide rates from 2023 to 2027, adjusting for the expected suicide reduction due to the fifth MPSP. Finally, we examined how many of our predicted trajectories would meet the fifth MPSP’s target of 18.2/100,000 in 2027. This approach allowed us to critically assess the feasibility of the policy goals set by the Korean government.
METHODS
Data sources and study population
Data on the finalized monthly suicide numbers from 2011 to 2022, the provisional monthly suicide numbers in 2023, and the projected and mid-year population from 2011 to 2023 were obtained from the Korean Statistical Information Service.13
Interrupted time series analysis
To evaluate the effect of the NAPSP, implemented from 2018 to 2022, this study utilized interrupted time series analyses comparing the actual and counterfactual outcomes in the post-intervention period.1415 Using Bayesian regression and Autoregressive Integrated Moving Average (ARIMA) models fitted on the monthly suicide data from 2011 to 2017, we predicted counterfactual time series of suicides from 2018 to 2022 (i.e., had the NAPSP not been implemented).1617 The Bayesian regression model with a negative binomial distribution was implemented using the ‘brm()’ function from the ‘brms’ package in R. The dependent variable in the models was the number of suicides, and the log of the mid-year population was treated as an offset. The models also incorporated seasonality and autocorrelation using ‘harmonic()’ and ‘ar()’ functions, respectively. The ARIMA model was fitted on monthly suicide rates (The Monthly Number of Suicides/The Mid-Year Population of The Year × 100,000) using the ‘auto.arima()’ function from the ‘forecast’ package. The counterfactual suicide rates predicted by the ARIMA model were then converted back to monthly suicide numbers by multiplying by the mid-year total population/100,000. The residual check of the ARIMA model is presented in the Supplementary Data 1. As metrics to compare the actual and counterfactual outcomes during the implementation of the NAPSP, we calculated the average and total differences between the actual and predicted suicide numbers, and the average of the ratio of the difference between the actual and predicted suicide numbers to the predicted suicide numbers. We also computed their 95% confidence intervals (CIs) as a measure of significance. We assumed these metrics to be indicative of the policy’s suicide reduction effects.
Prediction of future suicide rates
We employed the Bayesian regression and ARIMA models to predict future suicide rates from 2023 to 2027.1819 Using the same method as the models fitted in the interrupted time series analysis, the Bayesian regression and ARIMA models were fitted on monthly suicide numbers and rates from 2011 to 2022, respectively. For the Bayesian regression model, we generated point predictions of the monthly suicide numbers for the projected population from 2023 to 2027 using the ‘predict()’ function. For the ARIMA model, the ‘forecast()’ function was used to generate point predictions of the monthly suicide rates. In addition, we obtained 1,000 simulations, which are plausible future values incorporating inherent randomness and uncertainty, for each of the Bayesian regression and ARIMA models using the ‘posterior_predict()’ function and ‘simulate()’ function with bootstrapping. The number of future suicides predicted and simulated by the Bayesian regression model was converted to a suicide rate/100,000 of the projected population. For these point predictions and simulations, we sought to weight the possible suicide reduction effect calculated from the interrupted time series analysis. These were then converted into yearly suicide rates. The number of simulations where the 2027 suicide rate reached the target rate of 18.2/100,000 was counted. We plotted the actual suicide rates from 2011 to 2022 and the provisional suicide rate for 2023, followed by the predicted and simulated suicide rates through 2027. All statistical analyses were conducted using R (version 4.3.1; R Foundation for Statistical Computing, Vienna, Austria).
RESULTS
Effects of suicide prevention policy on suicide reduction
The interrupted time series analyses revealed that during the implementation of the NAPSP, the actual number of suicides was consistently higher than the predicted counterfactual number of suicides (Fig. 1). The Bayesian regression model showed an average monthly difference between the actual and counterfactual number of suicides of 155.9 (95% CI, 133.9–177.9), corresponding to a total of 9,354.6 excess suicides over the preceding trend during the policy period (Fig. 1A). The average ratio of the difference to the counterfactual number was 16.8% (95% CI, 14.3–19.4). Similarly, the ARIMA (0, 0, 4)(0, 0, 1)[12] model found an average monthly difference between the observed and counterfactual number of suicides of 127.3 (95% CI, 108.6–146.1), corresponding to a total of 7,639.0 excess suicides during the policy period (Fig. 1B). The average ratio of the difference to the counterfactual number was 13.1% (95% CI, 11.1–15.2). Taken together, these suggest that during the implementation of the NAPSP, the suicide rate did not decrease further from the underlying suicide trend. Thus, based on the suicide reduction effects of the past completed suicide prevention policy, we assumed that the implementation of the fifth MPSP would also not further reduce the suicide rate from the trend observed since 2011.
Fig. 1
Time series of actual and predicted counterfactual monthly suicide numbers before and after the implementation of the National Action Plan for Suicide Prevention. The dashed blue lines represent the predicted suicide numbers, and the surrounding blue area represents the 95% credible interval (A) or 95% confidence interval (B). The solid black line indicates the actual suicide numbers. The black bars represent the difference between the actual and counterfactual suicide numbers, while the gray bars represent the raw residuals.
ARIMA = Autoregressive Integrated Moving Average.
Predicting the 2027 suicide rate
Figs. 2 and 3 illustrate predicted and simulated future suicide rates from 2023 to 2027 based on the Bayesian regression and ARIMA models, respectively. All point predictions for the 2027 suicide rate are significantly above the target rate of 18.2/100,000 in 2027 for the fifth MPSP. The point prediction of the Bayesian regression predicted that the suicide rates will decrease moderately, reaching 23.5/100,000 in 2027 (Fig. 2). Similarly, the point prediction of the ARIMA (0, 0, 4)(0, 0, 1)[12] model predicted that the suicide rates will decrease moderately, reaching 23.9/100,000 in 2027 (Fig. 3). Only five of the 1,000 simulated 2027 suicide rates from the Bayesian regression model were below 18.2/100,000 (Fig. 2), but none of the simulations from the ARIMA model reached the target rate in 2027 (Fig. 3). Meanwhile, the provisional suicide rate in 2023, the first year of implementation of the fifth MPSP, was 26.9/100,000, which deviated significantly from the trajectory to the target rate in 2027.
Fig. 2
Annual suicide rates predicted by Bayesian regression model: fifth Master Plan for Suicide Prevention (2023–2027). The solid black line indicates the official suicide rates up until 2022, while the solid gray line represents the provisional suicide rate for 2023. The dashed blue lines and the gray area represent the point prediction and simulations of suicide rates from 2023 to 2027, respectively. The dotted red line illustrates the suicide reduction target set by the fifth Master Plan for Suicide Prevention.
Fig. 3
Annual suicide rates predicted by ARIMA model: fifth Master Plan for Suicide Prevention (2023–2027). The solid black line indicates the official suicide rates up until 2022, while the solid gray line represents the provisional suicide rate for 2023. The dashed blue lines and the gray area represent the point prediction and simulations of suicide rates from 2023 to 2027, respectively. The dotted red line illustrates the suicide reduction target set by the fifth Master Plan for Suicide Prevention.
ARIMA = Autoregressive Integrated Moving Average.
DISCUSSION
This study was conducted to assess the practicability of the suicide rate reduction target established by Korea’s most recent suicide prevention policy, the fifth MPSP (2023–2027). This policy aims to reduce the national suicide rate to 18.2/100,000 by 2027, a 30% decrease from the 2021 rate of 26/100,000.1112 Our interrupted time series analyses revealed that the previous NAPSP (2018–2022) had virtually no effect on reducing suicides. Assuming that the suicide reduction effects of the fifth MPSP would not significantly differ from those of the previous policy, our two different models collectively predicted that the suicide rate in 2027 would significantly exceed the policy target. Moreover, almost all of the 1,000 simulations from the prediction models failed to achieve the goal rate of 18.2. These findings, combined with the absence of evidence for any additional impact of the ongoing suicide prevention measures to curb the current suicide trend, and the higher-than-expected provisional 2023 suicide rate of 26.9/100,000, suggest that the 2027 target rate is likely unattainable based on the current trajectory. To the best of our knowledge, this is the first study to validate goal setting in suicide prevention policies using statistical methods.
The findings of this study are predicated on the assumption that suicide rates in Korea in the near future will continue the downward trend observed since 2011 and that the suicide reduction effects of the fifth MPSP will further reduce the rate to a comparable extent as the previous policy. Generally, in socioeconomically stable countries, suicide rates tend to remain steady or decrease slightly without dramatic shifts.920 Therefore, we hypothesized that future suicide rates in Korea could be forecasted based on suicide rates from the 2010s. Moreover, considering that the current suicide prevention policy is not markedly different from the previous one in terms of its strategies or budget, we estimated the suicide reduction effects of the previous suicide prevention policy and applied them to the predicted future suicide rates as the anticipated effects of the current policy.101112 Consequently, we discovered that the NAPSP, the prior suicide prevention policy, had no significant impact on reducing suicide compared to the preceding trend. Furthermore, our predictions largely indicate a more modest decrease in suicide rates after 2023 than the past decline in the 2010s. These findings suggest that unless the fifth MPSP has a dramatic suicide reduction effect beyond that of previous policies, it is unlikely to achieve its goal of a suicide rate of 18.2/100,000 in 2027.
The Korean government has set suicide reduction targets for its policies based on the rapid decline in suicide rates since 2011.101112 The NAPSP assumed a future reduction in the suicide rate by 7%, which is 170% of the average annual reduction rate of 4.18% between 2011 and 2016.10 This was expected to reduce the suicide rate from 25.6/100,000 in 2016 (13,092 suicides) to 17.0/100,000 in 2022 (8,727 suicides), preventing a total of 15,289 suicides over the five-year period. However, the actual suicide rate in 2022 was 25.2/100,000 (12,906 suicides), and our interrupted time series analyses estimated about 7,000 to 10,000 excess suicides during the policy period. Similarly, the fifth MPSP used the declining trend in suicide rates since 2011 as the rationale for setting its reduction target.1112 It noted that the suicide rate decreased by 23.3% from 2011 to 2017 (termed the ‘first decline phase’), but remained high from 2018 to 2021 due to frequent celebrity suicides and the ongoing COVID-19 pandemic. Drawing on the experience of the first decline phase, the fifth MPSP set a goal of reducing the suicide rate by more than 30% to achieve a rate of 18.2/100,000 in 2027 (termed the ‘second decline phase’). However, in 2023, the first year of the policy’s implementation, the provisional suicide rate was 26.9/100,000, up from the official rate of 25.2/100,000 in 2022.
The discrepancy between the objectives and outcomes of the Korean government’s suicide prevention strategies may stem from an overly optimistic perception of the suicide issue in Korea. The government anticipated that the decreasing trend in suicides since 2011 would continue and that its policies could accelerate this decline.101112 However, the reality is that the suicide rate has plateaued at approximately 25/100,000, and suicide prevention strategies have not been successful in reversing this trend.68 While suicide rates in Korea have seen a rapid decline since their peak in 2011, a significant portion of this decrease occurred around 2012–2013.20 In 2012, the production and sale of paraquat, a previously common suicide method, were prohibited. This straightforward and effective action has been proven to have substantially lowered the suicide rate.2122 However, subsequent suicide prevention policies have not proven to be any more effective, and the downward trend in suicide seems to be slowing.20 In this context, it seems that the Korean government’s misguided target setting of suicide prevention policies stems from a misunderstanding of past suicide trends, an overestimation of the effectiveness of other suicide prevention measures, and a lack of scientific evidence to predict future suicide trends.
To enhance the effectiveness of suicide prevention policies, particularly given the observed lack of initial impact, the government must adopt more proactive and innovative strategies. With rising suicide rates, it is imperative to implement aggressive measures specifically targeting high-risk populations, who are more vulnerable than the general population. Developing specialized suicide prevention strategies for these high-risk groups, including individuals with mental health issues, should be a priority in policy planning.23 While improvements in public awareness and revisions to suicide prevention laws have facilitated the activation of community-based support systems for suicide attempters, financial investment in community mental health centers and personnel responsible for managing suicide crises remains inadequate. In addition to reinforcing community management of suicide risk groups, it is essential to establish hospital-based case management systems supported by National Health Insurance financing to provide more extensive and comprehensive services.24 Furthermore, there is a critical need to explore and enhance social welfare support systems for individuals at risk of suicide due to economic hardships.25 Resource allocation remains a significant challenge, particularly in rural areas with limited mental health services. A thorough evaluation of the current mental health infrastructure is necessary to determine its capacity to meet the increased demand that effective suicide prevention policies would generate.26 Consequently, the government must assess the adequacy of funding allocated to these areas and consider significantly increasing the budget to ensure the successful implementation of these initiatives.8
This study had several limitations. First, the findings are based on statistical models that utilize historical suicide data and should not be considered definitive. This study employed suicide trends from 2011 onwards, which the government used to justify its suicide reduction targets, to evaluate the efficacy of the suicide prevention policy and to forecast future suicide rates. However, the results may fluctuate based on the timeframe of the suicide data and the modeling methodology used. Second, this study posits that the impact of the fifth MPSP will align with the effectiveness demonstrated by its predecessor, the NAPSP. It is also possible that the current suicide prevention policy will have a greater effect on reducing suicide rates than previous policies. However, policy effect sizes should not be estimated arbitrarily or optimistically without evidence. The outcomes of past policies can serve as a reasonable predictor of the effectiveness of future policies. Third, this study did not take into account socioeconomic changes that could influence suicide rates. Socioeconomic changes may have a delayed effect on suicide rates, and the socioeconomic indicators that may influence suicide rates in Korea are not yet clearly understood. Additional research is required to understand the interactive effects of suicide prevention policies and socioeconomic factors on suicide rates.
In conclusion, it seems highly unlikely that the Korean government’s suicide reduction target of 18.2/100,000 by 2027 will be achieved without significant changes in suicide prevention strategies and a substantial increase in budget. A suicide prevention policy should establish evidence-based and achievable suicide reduction goals. This will enable authorities to assess the effectiveness of their measures, adjust their approach, and be held accountable for their results. The Korean government needs to evaluate the effectiveness of its suicide prevention policy and adjust the target to a more attainable level.
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