Abstract
Bronchiectasis is commonly comorbid with depression and anxiety; therefore, bronchiectasis may be associated with an increased risk of suicide. We aimed to investigate whether suicidal risk is higher in individuals with bronchiectasis. We enrolled 3,903,636 individuals, including 50,975 individuals with bronchiectasis, from the Korean National Health Insurance Service dataset. Suicidal risk was significantly higher in individuals with bronchiectasis than in those without (adjusted hazard ratio [aHR], 1.27; 95% confidence interval [CI], 1.11–1.44). The increased risk of suicide was more evident in individuals with bronchiectasis who experienced hospitalization (aHR, 2.23; 95% CI, 1.32–3.77) and when they were underweight (aHR, 2.65; 95% CI, 1.78–3.96), diagnosed with depression (aHR, 3.35; 95% CI, 2.47–4.56) or cancer (aHR, 2.08; 95% CI, 1.18–3.66). In conclusion, bronchiectasis was associated with an increased risk of suicide, which was further heightened in individuals who experienced hospitalization or were underweight or had depression or cancer.
Keywords: Bronchiectasis, Suicide, Incidence, Risk Factors, Korea
Graphical Abstract
Bronchiectasis is a chronic respiratory condition characterized by persistent cough, sputum production, and recurrent infections.1 Individuals with bronchiectasis were prone to an increased risk of hospitalization and mortality.2 Suicide, a tragic event that should be prevented, is presumed to be more prevalent in individuals with chronic lung diseases, including idiopathic pulmonary disease, asthma, and chronic obstructive pulmonary disease, than in those without.3,4,5 Decreased quality of life and physical activity limitations resulting from chronic inflammatory pulmonary conditions of bronchiectasis could be associated with critical risk factors for suicide.6,7 For instance, depression—a significant cause of suicide—and anxiety are commonly found in individuals with bronchiectasis, affecting up to 65% of this population for depression and 54% for anxiety.8,9 Therefore, the risk of suicide may be higher among individuals with bronchiectasis. However, to our knowledge, no study has specifically evaluated whether suicidal risk increases among individuals with bronchiectasis.
We used data from the Korean National Health Insurance Service (NHIS), a retrospective, nationwide, representative longitudinal cohort.10 We included 4,234,415 individuals aged ≥ 20 years who participated in the 2009 health check-up. Of these, we excluded 320,374 individuals with missing data on any variables in the health screening examinations, 291 individuals who were diagnosed with bronchiectasis before the health examination, and 10,114 individuals who committed suicide within a year after bronchiectasis diagnosis. In total, 3,903,636 individuals (50,975 individuals with bronchiectasis and 3,852,661 individuals without bronchiectasis) were included in the final cohort.
The exposure was bronchiectasis, defined as claims under the International Classification of Diseases, 10th Revision (ICD-10) diagnosis code J47,11 recorded within the five years preceding the health check-up. Bronchiectasis was further divided to consider disease severity based on the healthcare utilization pattern–outpatients department (OPD) treatment only and experience of hospitalization.
The outcome was the suicide rate. Suicidal mortality was determined based on ICD-10 codes X60–X84 obtained through cross-referencing with mortality data from the Office of National Statistics.4 The follow-up period started one year after the diagnosis of bronchiectasis (or from the date of health screening for the control group) and extended until the occurrence of suicide, a censoring event, or until 31 December 2021.
Low income was defined as being in the lowest income quartile or receiving Medical Aid (bottom 3% of the population). Smoking status (never smoker vs. ever smoker), alcohol consumption, and regular exercise were determined using a self-reported questionnaire. Regular exercise was defined as moderate exercise for more than five days per week or vigorous exercise for more than three days per week. Underweight status was defined as a body mass index of < 18.5 kg/m2. Comorbidities were defined based on the relevant ICD-10 codes, with or without specific measurements.12
Differences between individuals with and without bronchiectasis were assessed using the χ2 test for categorical variables and the t-test for continuous variables. We used the Kaplan-Meier curve to compare the cumulative incidence of suicide between individuals with and without bronchiectasis. The risk of suicide was analyzed using multivariable Cox proportional hazards regression analyses. Variables included in the adjustment were age, sex, obesity (body mass index ≥ 25 kg/m2), smoking, alcohol consumption, physical activity, and low-income status. To explore the additive effects of bronchiectasis on suicidal risk, further subgroup analyses were performed using previously identified suicidal risk factors. A two-sided P value < 0.05 was considered statistically significant. All statistical analyses were conducted using SAS version 9.4 (SAS Institute Inc., Cary, NC, USA).
Table 1 presents the baseline characteristics of the total study population. Overall, individuals with bronchiectasis were older than those without bronchiectasis, as reflected by smaller proportions in the 20–39-year age range (8.9% vs. 31.2%) and higher proportions in the ≥ 60 years (49.6% vs. 21.0%; P < 0.001). More individuals with bronchiectasis were underweight (4.9% vs. 3.7%), and they were more likely to engage in regular physical activity (19.1% vs. 17.9%; P < 0.001). In terms of smoking status, those with bronchiectasis had a higher proportion of never smokers (68.1% vs. 60.3%; P < 0.001). Low income was more common in individuals with bronchiectasis (18.8% vs. 19.5%; P < 0.001). All assessed comorbidities were significantly more common among individuals with bronchiectasis than among those without (all P < 0.001).
Table 1. Baseline characteristics of the study population.
| Variables | Total population (N = 3,903,636) | Individuals without bronchiectasis (n = 3,852,661) | Individuals with bronchiectasis (n = 50,975) | P value | |
|---|---|---|---|---|---|
| Age, yr | < 0.001 | ||||
| 20–29 | 462,997 (11.9) | 461,664 (12.0) | 1,333 (2.6) | ||
| 30–39 | 741,244 (19.0) | 738,013 (19.2) | 3,231 (6.3) | ||
| 40–49 | 1,031,792 (26.4) | 1,023,521 (26.6) | 8,271 (16.2) | ||
| 50–59 | 8,343,74 (21.4) | 821,506 (21.3) | 12,868 (25.2) | ||
| 60–69 | 536,258 (13.7) | 521,794 (13.5) | 14,464 (28.4) | ||
| 70–79 | 257,748 (6.6) | 248,604 (6.5) | 9,144 (17.9) | ||
| ≥ 80 | 39,223 (1.0) | 37,559 (1.0) | 1,664 (3.3) | ||
| Sex, male | 2,113,644 (54.2) | 2,088,691 (54.2) | 24,953 (49.0) | < 0.001 | |
| BMI, kg/m2 | |||||
| Underweight (< 18.5) | 145,292 (3.7) | 142,795 (3.7) | 2,497 (4.9) | ||
| Normal weight (18.5–22.9) | 1,525,904 (39.1) | 1,505,773 (39.1) | 20,131 (39.5) | ||
| Overweight (23.0–24.9) | 960,244 (24.6) | 947,819 (24.6) | 12,425 (24.4) | ||
| Obesity (≥ 25) | 1,272,196 (32.6) | 1,256,274 (32.61) | 15,922 (31.2) | ||
| Regular physical activity | 699,487 (17.9) | 689,760 (17.9) | 9,727 (19.1) | < 0.001 | |
| Smoking status | < 0.001 | ||||
| Never smoker | 2,357,895 (60.4) | 2,323,202 (60.3) | 34,693 (68.1) | ||
| Past smoker | 542,616 (13.9) | 534,517 (13.9) | 8,099 (15.9) | ||
| Current smoker | 1,003,125 (25.7) | 994,942 (25.8) | 8,183 (16.1) | ||
| Alcohol drinker | 1,875,453 (48.0) | 1,858,330 (48.2) | 17,123 (33.6) | < 0.001 | |
| Low income | 762,422 (19.5) | 752,865 (19.5) | 9,557 (18.8) | < 0.001 | |
| Urban resident | 1,780,003 (45.6) | 1,756,668 (45.6) | 23,335 (45.8) | 0.415 | |
| Comorbidities | |||||
| Hypertension | 995,934 (25.5) | 976,626 (25.4) | 19,308 (37.9) | < 0.001 | |
| Diabetes mellitus | 339,558 (8.7) | 332,975 (8.6) | 6,583 (12.9) | < 0.001 | |
| Dyslipidemia | 678,954 (17.4) | 666,994 (17.3) | 11,960 (23.5) | < 0.001 | |
| Chronic kidney disease | 272,459 (7.0) | 266,945 (6.9) | 5,514 (10.8) | < 0.001 | |
| Depression | 119,439 (3.1) | 115,709 (3.0) | 3,730 (7.3) | < 0.001 | |
| COPD | 213,177 (5.5) | 199,586 (5.2) | 13,591 (26.7) | < 0.001 | |
| Asthma | 293,677 (7.5) | 279,449 (7.3) | 14,228 (27.9) | < 0.001 | |
| Tuberculosis | 352 (0.01) | 301 (0.01) | 51 (0.1) | < 0.001 | |
| Cancer | 50,306 (1.3) | 48,766 (1.3) | 1,540 (3.0) | < 0.001 | |
Data are presented as number (%) or mean ± standard deviation. Decimals were rounded to the first place, except for values < 0.1, which were rounded to the second place.
BMI = body mass index, COPD = chronic obstructive pulmonary disease.
During a median follow-up of 11.1 years (interquartile range, 11.1–11.6 years), suicide rates were higher in individuals with bronchiectasis compared to those without (0.5% vs. 0.3%; P < 0.001). This increased suicidal risk is also evident in the cumulative incidence plot (Fig. 1A, log-rank P < 0.001).
Fig. 1. Kaplan-Meier curves for suicide according to the presence or absence of bronchiectasis. (A) Main analysis, (B) stratified analysis.
OPD = outpatient department.
The risk of suicide was significantly higher in individuals with bronchiectasis than in those without (adjusted hazard ratio [aHR], 1.27; 95% confidence interval [CI], 1.11–1.44). As shown in Fig. 1B, this risk is more evident in individuals with bronchiectasis who experienced hospitalization (aHR, 2.23; 95% CI, 1.32–3.77) than in those who had OPD treatment only (aHR, 1.24; 95% CI, 1.09–1.41). The risk of suicide significantly increased in individuals with bronchiectasis when they were underweight (aHR, 2.65; 95% CI, 1.78–3.964), diagnosed with depression (aHR, 3.35; 95% CI, 2.47–4.56), or diagnosed with cancer (aHR, 2.08; 95% CI, 1.18–3.66) in subgroup analyses (Fig. 2).
Fig. 2. Forest plot for risk of death by suicide. Dash lines indicate 95% CI.
BE = bronchiectasis, IR = incidence rate, PY = person-years, aHR = adjusted hazard ratio, CI = confidence interval.
In this large-scale, nationwide, long-term study, we found that individuals with bronchiectasis had an increased risk of death by suicide compared to those without bronchiectasis. Furthermore, individuals with bronchiectasis who experienced hospitalization, were underweight, or had comorbid depression or cancers exhibited an even greater risk of death by suicide.
Recent concepts of bronchiectasis management involve earlier intervention to prevent disease progression and improve outcomes.1 Our finding supports this, suggesting that decreasing disease activity may not only improve physical outcomes but also psychological outcomes. Hospitalization is one of the critical markers in bronchiectasis severity, allocating higher points in both the bronchiectasis severity index and E-FACED score.13,14 Reflecting this, individuals who experienced hospitalization were vulnerable to suicide in our study. Progression of bronchiectasis itself may cause or aggravate mental diseases, and hospitalization-related alterations, such as physical deconditioning and microbiome disturbance, may be associated with poor mental health.15,16 Therefore, clinicians must be more vigilant in preventing hospitalization of individuals with bronchiectasis.
The reasons why underweight status increases the risk of suicide further in bronchiectasis are not fully explainable. Underweight individuals with bronchiectasis may face an increased risk of suicide due to the compounded effects of physical frailty and a more severe disease status related to worse lung function, more exacerbations, and chronic colonization by Pseudomonas aeruginosa. 17 Furthermore, although nutritional support as an adjunctive therapy for bronchiectasis has not been evaluated, nutritional and rehabilitation management may be beneficial in reducing suicide attempts.18
Although individuals with bronchiectasis have a higher prevalence of depression and anxiety than the general population,19 a previous study reported that depression was not associated with an increased risk of mortality among those with bronchiectasis.20 Accordingly, management of depression may not significantly improve the overall survival of individuals with bronchiectasis. However, our study suggests that appropriate management of depression and anxiety could prevent suicide, even though the proportion of suicidal deaths was not a major cause of death in bronchiectasis. Given that suicide is preventable,21 vigilant clinical attention to suicidal risk may help save certain individuals with bronchiectasis. Current clinical practice for bronchiectasis primarily focuses on physical health22; therefore, future guidelines should emphasize assessing and managing the psychological aspects of bronchiectasis.
Cancer is a well-known risk factor for suicide in the general population23 and an important comorbidity associated with an increased risk of overall mortality in bronchiectasis.20 Thus, it is not surprising that the combination of these two complicated conditions further increases the risk of suicide. A more comprehensive approach to addressing cancer and bronchiectasis status would help resolve the complex relationship between cancer, bronchiectasis, and suicidal risk.
This study has several limitations. First, misclassification may exist, as the study population was enrolled solely based on ICD-10 codes. Some patients could be misdiagnosed or have overlapping features with other chronic respiratory diseases.24 Second, complex backgrounds, including socioeconomic status, could not be assessed due to the limitations of the dataset. Third, the dataset also lacked certain important variables, such as computed tomography findings, pulmonary function test results, and bacterial colonization, and thus could not assess the etiology and severity of bronchiectasis.25,26 Fourth, the generalizability of the findings is limited, as the study included only Koreans.
In conclusion, bronchiectasis was associated with an increased risk of suicide, which was further heightened in individuals who experienced hospitalization, were underweight, or had depression or cancer. Preventive strategies to reduce the suicidal burden in individuals with bronchiectasis are needed.
Ethics statement
This study was approved by the Institutional Review Board (IRB) of Chungbuk National University Hospital (IRB No. 2024-06-019), and the requirement for informed consent was waived owing to the use of the anonymous patient identification system employed by the NHIS database.
Footnotes
Funding: This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (RS-2025-00557268 to HL and RS-2020-NR049557 to BY) and the research fund of Hanyang University (HY-202500000001668).
Disclosure: The authors have no potential conflicts of interest to disclose.
Data Sharing Statement: The data that support the findings of this study are available from the Korea Korean National Health Insurance Service (NHIS), but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are available from the authors upon reasonable request and with permission of the Korea NHIS.
- Data curation: Han K, Jung JH.
- Formal analysis: Han K, Jung JH.
- Supervision: Lee H.
- Validation: Lee H.
- Writing - original draft: Yang B, Kim SH, Lee H.
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