Druss and Pincus [16] | NHANES study of 7589 individuals aged 17–39 years from 26 states in USA between 1988 and 1994 | Cross-sectional | Suicidal ideation and attempts | Self-reported asthma | Asthma, chronic bronchitis and cancer showed a two-thirds increase in the presence of suicidal ideation. Around 1/5 of respondents with asthma, bronchitis, or cancer reported a past suicide attempt, compared to 1/18 in the general population. After adjusting for psychiatric and demographic factors, people with asthma were still significantly more likely to report a suicide attempt (aOR 4.34, p<0.001) and suicide ideation (aOR 1.69, p<0.01). | 5 (I=1, II=1, III=2, IV=0, V=1) |
Goodwin et al. [17] | 998 consecutive adult primary care patients aged 18–70 years attending appointments at the Associates in Internal Medicine clinic (Columbia-Presbyterian Medical Centre, Manhattan, NY, USA) between October 1998 and April 1999 | Cross-sectional | Suicidal ideation | Asthma diagnosis from primary-care physicians | Asthma was significantly associated with suicidal ideation (OR 1.9, 95% CI 1.03–3.4) and with panic attack after controlling for socio-demographic factors and mental disorders. Asthma was not significantly associated with major depression, generalised anxiety disorder, alcohol, or drug use disorders. | 3 (I=0, II=1, III=1, IV=0, V=1) |
Goodwin and Marusic [18] | MECA study of 1285 youths aged 9–17 years from four sites in USA | Cross-sectional | Suicidal ideation (“In the past 6 months have you thought about suicide or killing yourself?”) | Parental reports of past hospitalisation for asthma | Youths with asthma were significantly more likely to report suicidal ideation than those without asthma, even when adjusting for sociodemographic characteristics and comorbid mental disorders (aOR 3.25, 95% CI 1.04–10.1). | 3 (I=1, II=1, III=0, IV=0, V=1) |
Goodwin and Eaton [19] | Baltimore (MD, USA) follow-up of the Epidemiologic Catchment Area Study: 3481 community participants aged ≥18 years in USA studied in 1981 (wave 1) and 1982 (wave 2); 1920 individuals (74% of the original sample) followed-up in 1993–1996 (wave 3) | Cohort study | Suicidal ideation and attempts measured at three time points | Self-reported asthma | Several associations between asthma and suicidality at different waves were found to be significant. However, current asthma at wave 1 of the study was associated with a significantly increased risk of suicidal ideation at wave 2, after controlling for sex, age, race, asthma treatment and lifetime major depression (OR 2.3, 95% CI 1.03–5.25). Current asthma at wave 1 was also associated with significantly increased risk of suicide attempts at wave 2 when controlling for the same variables (OR 3.54, 95% CI 1.4–8.99). Analysis at wave 3 of the study was not included as the cell sizes became too small for comparison due to participant attrition. | 5 (I=1, II=1, III=1, IV=1, V=1) |
Bender [20] | YRBS study of 13 917 youth in school grades 9–12 from 40 states and 21 cities in USA in 2005 | Cross-sectional | Suicidal ideation and attempts | Self-reported lifetime diagnosis of asthma and asthma symptoms in past 12 months | Students with asthma were significantly more likely to report depressive symptoms, suicidal thoughts, plans, actions and injuries than their nonasthmatic peers: 31% reported considering suicide compared to 16.2% (p<0.001) and 17.9% had made a suicide attempt compared to 8.5% of the nonasthmatic group (p<0.001). | 5 (I=1, II=1, III=2, IV=0, V=1) |
Nomura et al. [21] | Regional random sample of 2694 individuals born between 1960 and 1964 (perinatal conditions measured at delivery); 1525 were followed-up in adulthood (27–33 years in 1992–1994) in Baltimore (MD, USA) | Cohort study | Suicidal ideation | Self- reported current or past asthma | Offspring with suicidal ideation had a significantly increased risk of comorbid asthma when confounding factors were adjusted for (aOR 2.8, 95% CI 1.4–5.8). There was no evidence that perinatal risk factors increased the risk of comorbid suicidal ideation and asthma. | 5 (I=1, II=1, III=1, IV=1, V=1) |
Clarke et al. [22] | NCS-R study of 5692 English-speaking individuals aged ≥18 years and living in USA between February 2001 and April 2003 | Cross-sectional | Suicidal ideation and attempts | Self-reported diagnosed asthma | A statistically significant association between asthma and suicidal ideation with attempts (OR 1.98, 95% CI 1.42–2.76), but not suicidal ideation alone (OR 1.09, 95% CI 0.81–1.45) was found. After controlling for age, sex and race/ethnicity, the relationship between suicide attempts and asthma reduced by 6.1% reducing by a further 16% when smoking and nicotine dependence was accounted for. In addition, the association decreased by 12.4% when depression, panic disorder and alcohol dependence or abuse were adjusted for; however, the association remained significant (aOR 1.53, 95% CI 1.06–2.21). | 5 (I=1, II=1, III=2, IV=0, V=1) |
Kuo et al. [23] | The Study of Asthma and Allergy of 162 766 high-school students aged 11–16 years in October 1995–June 1996 and their parents was linked with the national death certification system in Taiwan up to December 2007 | Cohort study | Suicide mortality | Self-reported current and previous asthma symptoms | When comparing groups with current asthma, previous asthma and no asthma, the only significant between-group effect was observed in suicide deaths: 11 per 100 000 person-years, 8.5 per 100 000 person-years and 4.3 per 100 000 person-years, respectively (p<0.001). There were no significant differences in natural deaths between the three groups. After adjusting for sex, age, personal and family cigarette smoking and allergic rhinitis, the current-asthma group had a significantly higher likelihood of suicide mortality than the no-asthma group (HR 2.26, 95% CI 1.43–3.43), but not the previous-asthma group. Particular symptoms of asthma (exercise wheezing, night cough and severe wheezing) were significantly associated with suicide risk after adjusting for covariates. Having a greater number of symptoms increased risk of suicide. | 6 (I=1, II=1, III=2, IV=1, V=1) |
Bae et al. [24] | The 2008 KYRBWS study of 75 238 Korean youths attending middle or high school | Cross-sectional | Self-reported suicidal ideation and attempts | Self-reported diagnosis and treatment of asthma | The results of the study showed higher prevalence of suicidal ideation and attempts in current and former asthmatics when compared to their peers without asthma. These results remained significant when controlling for confounding factors for both considering suicide (OR 1.36, 95% CI 1.19–1.55 and OR 1.40, 95% CI 1.27–1.54, respectively) and attempting suicide (OR 1.55, 95% CI 1.25–1.92 and OR 1.54, 95% CI 1.29–1.84, respectively). aOR also showed a significant relationship between current or former asthma, suicidal ideation and current cigarette use and cigarette use before the age of 13 years. Suicidal ideation was an effect modifier of the relationship between asthma and cigarette use. | 5 (I=1, II=1, III=2, IV=0, V=1) |
Chan et al. [25] | National Survey of Health Promotion Knowledge, Attitudes, and Practice of 3853 elderly adults aged >65 years in Taiwan in 2002–2003 | Cross-sectional | Suicidal ideation | Self-reported diagnosis of asthma | Univariate analysis showed significant association between suicidal ideation and asthma (OR 2.84, 95% CI 1.76–4.58). Asthma did not remain a significant predictor of suicidal behaviours in a multivariate logistic regression analysis. | 4 (I=1, II=1, III=1, IV=0, V=1) |
Christiansen and Stenager [26] | 3465 children and youths born between 1983 and 1989 who attempted suicide were matched with 20 population controls with identical age and sex (69 300 controls) using Danish national population registers and followed until 2005 | Nested case–control | Suicide attempt | Hospital records of asthma treated in a somatic hospital | For both male and female patients, treatment for asthma was a significant risk factor for attempted suicide (rate ratio (95% CI) 1.57 (1.15–2.14) (p<0.05) and 1.88 (1.49–2.35) (p<0.0001), respectively). The risk of suicide was greatest in the first couple of weeks after contact with the somatic department. When adjusting for possible confounding variables (i.e. child's psychiatric history, parent's psychiatric history, level of income and education) asthma was not an independent risk factor for suicide (rate ratio (95% CI) for males 1.11 (0.78–1.59) and females 1.02 (0.83–1.24)). | |
Chung and Joung [27] | 13 958 youths in USA who completed the YRBS and 48 814 Korean youths who completed the Korean Youth Behavioral Risk Factor Surveillance Survey aged 12–18 years in 2007 | Cross-sectional | Suicidal ideation and attempts | Self-reported diagnosis of asthma | Results indicated that a medical diagnosis of asthma was a significant risk factor for both suicidal ideation (aOR 1.15, 95% CI 1.06–1.25) and attempt (aOR 1.44, 95% CI 1.28–1.63) in the Korean youth sample, but not in the USA youth sample. | 6 (I=1, II=1, III=2, IV=1, V=1)5 (I=1, II=1, III=2, IV=0, V=1) |
Goodwin et al. [28] | 6584 adults aged 20–39 years who participated in NHANES III between 1988 and 1994 in USA | Cross-sectional | Suicidal ideation and attempts | Self-reported diagnosed asthma | Compared to individuals without asthma, current asthma status was associated with higher risk of suicidal ideation (OR 2.07, 95% CI 1.28–3.34) and suicide attempt (OR 3.83, 95% CI 2.32–6.34), which remained statistically significant (although somewhat reduced) after controlling for demographic characteristics, smoking, depression, dysthymia, mania and allergy (suicide ideation OR 1.77, 95% CI 1.11–2.84 and suicide attempt OR 3.26, 95% CI 1.97–5.39). There was no significant relationship between former asthma and suicide ideation or attempt when the same variables were adjusted for. | 4 (I=1, II=1, III=1, IV=0, V=1) |
Webb et al. [29] | Data from UK family practices registered with the GPRD, linked with national mortality records of 873 adult suicide cases matched by age and sex with 17 460 living controls between 2001 and 2008 | Nested case–control | Suicide mortality | Asthma diagnosis from primary-care records | Overall, there was no higher suicide risk in those with any of the 11 physical illnesses studied combined (aOR 0.89, 95% CI 0.75–1.04). Asthma was not significantly associated with increased suicide mortality before or after controlling for depression (aOR 0.84, 95% CI 0.66–1.08). 64.7% of asthma cases had depression, which was the second most frequent comorbidity after back pain. | 6 (I=1, II=1, III=2, IV=1, V=1) |
Webb et al. [30] | Routinely collected UK primary-care records of 2306 self-harm cases and 46 120 age- and sex-matched controls from the GPRD between 2001 and 2008 Age at first episode of self-harm ranged from 17 to 87 years | Nested case–control | Self-harm | Asthma diagnosis from primary-care records | Overall, patients diagnosed with any of the included physical illnesses had almost 50% higher risk of self-harm. Separate analysis showed that 9 out of the 11 illnesses had significantly increased risk; however, when controlling for depression, only asthma (OR 1.17, 95% CI 1.03–1.34), back pain and epilepsy remained significant. Having ≥2 comorbid medical conditions significantly increased the risk of self-harm in women but not men when controlling for depression. | 6 (I=1, II=1, III=2, IV=1, V=1) |
Bandiera et al. [31] | 1550 Puerto Rican youths aged 11–16 years and living in the South Bronx (New York, NY, USA), San Juan and Caguas (Puerto Rico) participating in the Boricua Youth Study of antisocial behaviours and other psychiatric disorders (wave 3) in 2000–2004 | Cross-sectional | Self-reported suicidal thoughts and ideation, past suicide attempts and suicidal plans within the past year | Parental reports of asthma in past year | Those with asthma were ∼1.7 times (95% CI 1.11–2.64) more likely to experience suicidal ideation or behaviour than those without asthma. This association was significant even when controlling for demographics, socioeconomic status, major depression, conduct disorder, PTSD, cigarette smoking and stressful life events. | 5 (I=1, II=1, III=1, IV=0, V=1) |
Bolton et al. [32] | 2100 individuals from Manitoba (Canada) who died by suicide between 1996 and 2009 were matched with 6300 general population controls 8641 individuals with suicide attempts were compared to 25 923 matched controls Data were obtained from the Population Health Research Data Repository at the Manitoba Centre for Health Policy Ages ranged from those born in 1940 and earlier to those born in 1991 and later | Nested case–control | Suicide mortality and suicide attempts | Physician-diagnosed asthma as recorded in the Manitoba health registry | In unadjusted models, asthma was significantly associated with increased risk of suicide mortality (OR 1.50, 95% CI 1.32–1.71; p<0.001). In the adjusted model, asthma was no longer significantly associated with suicide risk overall (aOR 1.03, 95% CI 0.88–1.22); however, the risk remained significant in women (aOR 1.41, 95% CI 1.06–1.86; p<0.05). Asthma was associated with risk of suicide attempts after adjusting for ADG count, depression, anxiety disorders, substance abuse, schizophrenia, dementia and all other physical disorders (aOR 0.84, 0.75–0.93; p<0.001). | 6 (I=1, II=1, III=2, IV=1, V=1) |
Crump et al. [33] | National cohort of 7 140 589 Swedish adults aged ≥18 years were followed for suicide mortality using the Swedish death registry between 2001 and 2008 | Cohort study | Suicide mortality | Diagnosed asthma recorded in outpatient and hospital registries | Univariate analysis indicated that asthma (p=0.02) was more prevalent among women who died by suicide compared to the rest of the population. Further multivariate analysis indicated that a number of somatic disorders, including asthma, were significant independent risk factors for suicide among both men and women (aHR ∼1.4–2.1). | 6 (I=1, II=1, III=2, IV=1, V=1) |
Singhal et al. [34] | Cohort from nationwide dataset of English Hospital Episode Statistics linked with mortality data from 1999 to 2011 2 500 814 individuals with asthma were included and ages ranged from children to adults (10–>65 years) | Cohort study | Self-harm and suicide mortality | Hospital admissions for asthma | Asthma was associated with an increased risk of self-harm (rate ratio 1.8, 95% CI 1.8–1.9), the highest risk being in those aged 45–64 years (rate ratio 2.2, 95% CI 2.1–2.2). Those suffering from asthma were also significantly more likely to die by suicide than those in the reference cohort (rate ratio 1.2, 95% CI 1.1–1.3; p<0.05). | 6 (I=1, II=1, III=2, IV=1, V=1) |