death by suicide is a leading cause of death,1 and initiatives to advance suicide prevention programmes are a high priority in many countries.2 harmful alcohol use has been recognised as a strong risk factor for suicide death.2 in psychological autopsy studies , alcohol use disorder was strongly associated with suicide death ( or=5.2 , 95% ci 3.3 to 8.3),3 and heavy alcohol use was also strongly linked with suicide death ( or=6.2 , 95% ci 5.6 to 6.9 in men).4 in a recent systematic review of the prospective studies , however , the magnitude of the association between alcohol use disorder and suicide death was reported to be moderate ( pooled risk ratio=1.74 , 95% ci 1.26 to 2.21 ) .
the strong associations reported in psychological autopsy studies and case  control studies may have resulted , at least in part , from several biases such as surrogate interview bias and recall bias .
furthermore , when usual alcohol consumption rather than alcohol use disorder is considered in the general population , evidence of the impact of usual alcohol consumption on suicide death is less than convincing .
control studies based on a prospective cohort , have indicated that alcohol consumption was not associated with a higher risk of suicide death , compared to no alcohol consumption , even in the group with the highest consumption in each study,511 with a few exceptions.12 
 13 overall , the association between usual alcohol consumption and suicide death is unclear .
since the majority of adults drink alcohol at some point in their life , a better understanding of usual alcohol consumption and suicide death should inform decision - making for better suicide prevention strategies in the general population .
the purpose of this study was to prospectively examine the association of usual alcohol intake - related variables including alcohol intake frequency , average alcohol consumption and quantity of alcohol consumed on a drinking day with suicide death in a community dwelling elderly population in korea .
we tried to elucidate questions such as whether greater usual alcohol consumption is associated with a greater risk of suicide death ( dose  response relationship ) , and whether moderate alcohol consumption ( below 5 drinks / week , or 4 or fewer drinking days a month ) has a protective effect against suicide death compared to abstaining completely .
the kangwha cohort study was established in march 1985.14 
 15 among 9378 residents of kangwha county in korea who were 55  years or older as of february 1985 , 6372 persons ( 67.9% ) participated in the survey .
participants who were lost to follow - up after the initial survey ( n=39 ) were excluded , as were those with missing information about drinking status ( n=2 ) , their body mass index ( bmi ; n=143 ) , or other covariates ( n=25 ) . in the end , a total of 6163 elderly ( 2635 men ; 3528 women ) were included as a study population .
the institutional review board of yonsei university ( approval no . 4 - 2007 - 0182 )
no to the question ,  do you drink alcohol? the drinking frequency was reported as daily , almost daily , 23 times a week , 14 times a month or 412 times a year . the question concerning the type of alcoholic beverage and the amount of alcohol consumption was ,
 how much ( in doe ( 1800  ml ) , hop ( 180  ml ) , bottles or glasses ) do you drink of a type of alcoholic beverage? alcohol consumption ( alcohol in grams ) per week was estimated by multiplying the amount of alcohol consumption per drinking day ( ml ) by the alcohol content in the particular type of alcoholic beverage , the drinking days per week , and the specific gravity of alcohol ( 0.8 ) . a different score for drinking days per week
was assigned to each drinking frequency ( daily : 7.0 ; almost daily : 5.5 ; 23 times a week : 2.5 ; 14 times a month : 0.625 ; 412 times a year : 0.163 ; non - drinking : 0 ) .
participants were asked to fill in up to two types of alcoholic beverage they usually consume on one drinking day .
the amount of alcohol consumption was calculated for each type and summed . among drinkers ,
the alcohol content and the bottle volume of each type of alcoholic beverage were determined on the basis of data from the year 1985 .
soju is a distilled alcoholic beverage , a type of liquor , and makkoli is an unfiltered alcoholic beverage made from rice , both native to korea .
soju had 25% alcohol and makkoli 6% alcohol at the time of the survey for the kangwha cohort study in 1985 .
the amount of ethanol was 10  g in a glass of soju and 9.6  g in a glass of makkoli .
the alcohol frequency was merged into four groups in further analysis : daily , 26  days a week ( almost daily and 23 times a week combined ) , 4 or fewer days a month ( 14 times a month and 412 times a year combined ) , and non - drinkers . the alcohol intake amount ( grams of alcohol ) per week was classified into four groups ( grams of alcohol per week ( drinks per week , with 1 drink as 14  g of alcohol16 ; non - drinkers , < 70 ( < 5 drinks ) ; 70209 ( 514 ) , 210419 ( 1529 ) , and 420 ( 30 ) ) .
the amount consumed ( grams of alcohol ) per drinking day was classified into four groups ( grams of alcohol per drinking day ( drinks per occasion ) ; non - drinkers , < 70 ( < 5 drinks ) ; 70139 ( 59 ) , and 140 ( 10 ) ) . one standard drink was considered to be around 14  g.16 the alcohol intake frequency ( number of days ) per week , alcohol intake volume per week , and alcohol intake amount per drinking day were also analysed as continuous variables . trained investigators interviewed each participant using a structured questionnaire for sociodemographic factors and health - related factors including alcohol intake - related variables , smoking status and marital status .
bmi was calculated as the weight in kilograms divided by the square of the height in metres ( kg / m ) .
more details on the data collection have been described elsewhere.14 
 15 data on deaths from suicide from 1 january 1992 to 31 december 2008 were confirmed by national death records from the national statistical office of korea .
data on those who died from march 1985 to 31 december 1991 were collected either through calls or visits of trained surveyors twice a year , or from records of burial and death certificates at local administrative branch offices in each study region .
follow - up was performed through record linkage at the national level and was complete , except for the case of emigrants .
the  test and analysis of variance were performed to compare individual characteristics by drinking status .
cox proportional hazards models were used to calculate hrs associated with alcohol intake - related variables .
the covariables included in the cox model were age at enrolment ( continuous variable ) , hypertension ( hypertension , no hypertension ; an indicator for cardiovascular health6 ) , smoking ( never smoker , past smoker , or current smoker ; participants were asked to answer 
i quit smoking to the question ,  do you smoke cigarettes? ) , bmi ( kg / m ; < 18.5 , 18.524.9 ( reference ) , or 25.0 ) , self - rated health ( good or fair , or poor ) , marital status ( living with a spouse , not living with a spouse ) , education ( ever , never ) and occupation ( non - agriculture , agriculture ) .
since the number of suicide deaths is small , there is a possibility of overfitting when all those potential confounders are included in the cox model ; thus , additional analysis was performed , including only those variables with the model p value < 0.2 for the wald test in the univariate cox analysis : sex , smoking status , self - rated health compared to the same age group , marital status and occupation .
additionally , analysis according to the follow - up period ( 19851996 vs 19972008 ) was performed to examine whether alcohol - related suicide death may differ by period after alcohol intake assessment .
hypertension , marital status and a dummy variable for bmi ( 25  kg / m ) showed some evidence of a violation of the assumption ( p<0.1 ) .
therefore , additional analyses after exclusion of these three variables , or exclusion of the hypertension and bmi variables after stratification of marital status ( since marital status ( p=0.013 ) , was associated with suicide death in univariate cox analysis , while bmi ( p=0.51 ) and hypertension ( p=0.36 ) were not ) were performed . subgroup analysis ,
analysis with different alcohol intake variables , and additional analysis with different covariables served as a sensitivity analysis .
all statistical analyses were performed using sas v.9.4 ( sas inc , cary , north carolina , usa ) .
the p value was calculated with two - sided tests , and a statistical significance level of 0.05 was applied .
the kangwha cohort study was established in march 1985.14 
 15 among 9378 residents of kangwha county in korea who were 55  years or older as of february 1985 , 6372 persons ( 67.9% ) participated in the survey .
participants who were lost to follow - up after the initial survey ( n=39 ) were excluded , as were those with missing information about drinking status ( n=2 ) , their body mass index ( bmi ; n=143 ) , or other covariates ( n=25 ) . in the end , a total of 6163 elderly ( 2635 men ; 3528 women ) were included as a study population .
the institutional review board of yonsei university ( approval no . 4 - 2007 - 0182 )
 do you drink alcohol? the drinking frequency was reported as daily , almost daily , 23 times a week , 14 times a month or 412 times a year .
the question concerning the type of alcoholic beverage and the amount of alcohol consumption was ,  how much ( in doe ( 1800  ml ) , hop ( 180  ml ) , bottles or glasses ) do you drink of a type of alcoholic beverage? alcohol consumption ( alcohol in grams ) per week was estimated by multiplying the amount of alcohol consumption per drinking day ( ml ) by the alcohol content in the particular type of alcoholic beverage , the drinking days per week , and the specific gravity of alcohol ( 0.8 ) .
a different score for drinking days per week was assigned to each drinking frequency ( daily : 7.0 ; almost daily : 5.5 ; 23 times a week : 2.5 ; 14 times a month : 0.625 ; 412 times a year : 0.163 ; non - drinking : 0 ) .
participants were asked to fill in up to two types of alcoholic beverage they usually consume on one drinking day .
the amount of alcohol consumption was calculated for each type and summed . among drinkers ,
the alcohol content and the bottle volume of each type of alcoholic beverage were determined on the basis of data from the year 1985 .
soju is a distilled alcoholic beverage , a type of liquor , and makkoli is an unfiltered alcoholic beverage made from rice , both native to korea .
soju had 25% alcohol and makkoli 6% alcohol at the time of the survey for the kangwha cohort study in 1985 .
the amount of ethanol was 10  g in a glass of soju and 9.6  g in a glass of makkoli .
the alcohol frequency was merged into four groups in further analysis : daily , 26  days a week ( almost daily and 23 times a week combined ) , 4 or fewer days a month ( 14 times a month and 412 times a year combined ) , and non - drinkers . the alcohol intake amount ( grams of alcohol ) per week
was classified into four groups ( grams of alcohol per week ( drinks per week , with 1 drink as 14  g of alcohol16 ; non - drinkers , < 70 ( < 5 drinks ) ; 70209 ( 514 ) , 210419 ( 1529 ) , and 420 ( 30 ) ) . the amount consumed ( grams of alcohol ) per drinking
day was classified into four groups ( grams of alcohol per drinking day ( drinks per occasion ) ; non - drinkers , < 70 ( < 5 drinks ) ; 70139 ( 59 ) , and 140 ( 10 ) ) . one standard drink was considered to be around 14  g.16 the alcohol intake frequency ( number of days ) per week , alcohol intake volume per week , and alcohol intake amount per drinking day were also analysed as continuous variables .
trained investigators interviewed each participant using a structured questionnaire for sociodemographic factors and health - related factors including alcohol intake - related variables , smoking status and marital status .
bmi was calculated as the weight in kilograms divided by the square of the height in metres ( kg / m ) .
data on deaths from suicide from 1 january 1992 to 31 december 2008 were confirmed by national death records from the national statistical office of korea .
data on those who died from march 1985 to 31 december 1991 were collected either through calls or visits of trained surveyors twice a year , or from records of burial and death certificates at local administrative branch offices in each study region .
follow - up was performed through record linkage at the national level and was complete , except for the case of emigrants .
the  test and analysis of variance were performed to compare individual characteristics by drinking status .
cox proportional hazards models were used to calculate hrs associated with alcohol intake - related variables .
the covariables included in the cox model were age at enrolment ( continuous variable ) , hypertension ( hypertension , no hypertension ; an indicator for cardiovascular health6 ) , smoking ( never smoker , past smoker , or current smoker ; participants were asked to answer 
i quit smoking to the question ,  do you smoke cigarettes? ) , bmi ( kg / m ; < 18.5 , 18.524.9 ( reference ) , or 25.0 ) , self - rated health ( good or fair , or poor ) , marital status ( living with a spouse , not living with a spouse ) , education ( ever , never ) and occupation ( non - agriculture , agriculture ) . since the number of suicide deaths is small , there is a possibility of overfitting when all those potential confounders are included in the cox model ; thus , additional analysis was performed , including only those variables with the model p value < 0.2 for the wald test in the univariate cox analysis : sex , smoking status , self - rated health compared to the same age group , marital status and occupation .
additionally , analysis according to the follow - up period ( 19851996 vs 19972008 ) was performed to examine whether alcohol - related suicide death may differ by period after alcohol intake assessment .
hypertension , marital status and a dummy variable for bmi ( 25  kg / m ) showed some evidence of a violation of the assumption ( p<0.1 ) .
therefore , additional analyses after exclusion of these three variables , or exclusion of the hypertension and bmi variables after stratification of marital status ( since marital status ( p=0.013 ) , was associated with suicide death in univariate cox analysis , while bmi ( p=0.51 ) and hypertension ( p=0.36 ) were not ) were performed .
subgroup analysis , analysis with different alcohol intake variables , and additional analysis with different covariables served as a sensitivity analysis .
all statistical analyses were performed using sas v.9.4 ( sas inc , cary , north carolina , usa ) .
the p value was calculated with two - sided tests , and a statistical significance level of 0.05 was applied .
during 88  376 person - years of follow - up ( mean : 14.3 person - years ) , 37 men and 24 women died by suicide .
the average ( sd ) age at baseline of the korean elderly was 66.6 ( 7.9 ) years .
current drinkers were slightly younger than non - drinkers , and they tended to be men , current smokers , healthy , living with a spouse and have more formal education , compared with non - drinkers ( table 1 ) .
baseline characteristics of the korean elderly according to alcohol intake status one - way analysis of variance . measured blood pressure 140/90  mm  hg or on regular medication .  no formal education , not even elementary school .
1 standard drink considered to be approximately 14  g according to the national institute on alcohol abuse and alcoholism of the usa .
, current drinkers had a higher hr of suicide than non - drinkers and higher frequency and amount of alcohol intake were associated with a higher hr of suicide ( table 2 ) .
two or more days of alcohol intake per week , 70  g ( 5 drinks ) or more of alcohol consumption per drinking day , and 210  g ( 15 drinks ) or more alcohol consumption per week were associated with higher suicide mortality , compared with non - drinkers , in the unadjusted analysis . after adjustment for potential confounders ,
adjusted hrs of one drinking day increase per week , each 70  g ( 5 drinks ) higher alcohol intake per drinking day , and each 140  g ( 10 drinks ) higher alcohol intake per week , were 1.17 , 1.38 and 1.12 , respectively ( table 2 ) .
current smokers and people with poor self - rated health had higher suicide mortality , after adjustment for other risk factors including alcohol intake status ( see online supplementary table s1 ) .
crude death rates and hrs of suicide death by alcohol consumption - related variables in the korean elderly * death rate per 100  000 person - years .
adjusted for age at enrolment ( continuous variable ) , sex ( men , women ) , smoking status ( current smoker , past smoker , never smoker ) , body mass index ( kg / m ; < 18.5 , 18.524.9 , 25 ) , hypertension ( measured blood pressure 140/90  mm  hg or on regular medication ; yes , no ) , self - rated health compared to the same age group ( good or fair , poor ) , marital status ( living with a spouse , not living with a spouse ) , education ( ever , never ) and occupation ( non - agriculture , agriculture ) .
1 standard drink as around 14  g according to the national institute on alcohol abuse and alcoholism of the usa . in a stratified analysis by sex ,
given the same alcohol intake , women seemed to have a higher relative risk of suicide associated with alcohol consumption , compared with men ( figure 1 ) .
however , p values of the interaction of sex and alcohol intake - related variables with suicide were above 0.05 , due to the small number of suicide deaths .
hrs associated with alcohol consumption did not differ between the first half ( 19851996 ) and the latter half ( 19972008 ) of the follow - up ( see online supplementary figure s1 ) .
the hrs of alcohol consumption variables from the sensitivity analysis with reduced covariables to deal with potential overfitting , or violation of the proportional hazards assumption , were generally the same as in the main analysis ( see online supplementary table s2 ) .
covariables included in the cox model were age at enrolment ( continuous variable ) , smoking status ( current smoker , past smoker , never smoker ) , body mass index ( kg / m ; < 18.5 , 18.524.9 , 25 ) , hypertension ( measured blood pressure 140/90  mm  hg or on regular medication ; yes , no ) , self - rated health compared to the same age group ( good or fair , poor ) , marital status ( living with a spouse , not living with a spouse ) , education ( ever , never ) and occupation ( non - agriculture , agriculture ) .
in our community - based cohort study among the korean rural elderly , more frequent drinking , a larger amount of alcohol consumption per drinking day and a larger amount of average alcohol consumption were associated with a higher risk of death by suicide .
one drinking day increase per week , a 70  g ( 5-drink ) increase in the average alcohol intake per drinking day , and a 140  g ( 10-drink ) increase in the average alcohol intake per week were associated with a 17% , 38% and 12% higher risk of death by suicide , respectively , after adjustment for age , sex , socioeconomic status , behavioural and health - related potential confounders in the korean elderly .
few prospective cohort studies have ever examined the impact of the quantity of usual alcohol consumption on suicide mortality after adjustment for potential confounders.57 
 1113 
 17 among community - based cohort studies,1113 in 43  383 japanese men from a public health centre - based cohort , occasional drinkers had the lowest risk of death by suicide , while non - drinkers and heavy drinkers ( 414  g alcohol per week ) had a higher risk;11 in another public health centre - based cohort study in 22  804 japanese men ( mean age : 60  years ) , alcohol consumption was linearly associated with suicide death;13 in 128  934 participants of the northern california medical care programme in the usa , greater alcohol consumption ( especially 6 drinks per day ) was associated with higher suicide death.12 among occupation - based cohort studies,57 
 17 in around 49  000 norwegian conscripts , high alcohol consumption ( > 250  g / week ) was associated with a non - significantly increased risk of suicide ( hr=1.7 , 95% ci 1.0 to 2.8 ) compared to moderate consumption ( 1100  g / week);17 among 89  299 physicians and 47  654 health professionals in the usa , alcohol consumption was not associated with suicide death;5 
 7 among 1.3 million korean adults , mostly government and school employees , moderate alcohol intake ( 124  g / day ) , but not high alcohol intake ( 25  g / day ) , was associated with higher suicide mortality and alcohol intake was not linearly associated with suicide death.6 additionally , among nested case 
control studies based on prospective cohorts in the usa , the usual amount of alcohol consumption was not associated with suicide death in the community elderly aged 65  years and older , elderly in a retirement community and former college students.810 among prospective studies based on a community cohort , three studies examined the associations in the mainly elderly population with a mean age of 60  years or above.9 
 10 
 13 as noted in the previous paragraph , prospective studies have produced inconsistent results on the association between usual alcohol consumption and suicide death .
however , results from community - based cohort studies , including the current study , indicated that usual alcohol consumption may be linearly associated with suicide death in the community - dwelling population , at least among current drinkers.1113 additionally , our study does not support a protective effect of moderate alcohol consumption against suicide mortality in accordance with other,12 
 13 but not all,11 community - based cohort studies .
as for occupation - based cohort studies , usual alcohol consumption did not generally show a linear dose 
, participants were mostly healthier , and had a higher socioeconomic status and potentially easier access to healthcare and other resources than the general population.57 they also had a generally lower alcohol consumption .
these factors combined might affect the association between usual alcohol intake and suicide mortality in previous occupation - based cohort studies .
prospective cohort studies have seldom evaluated the association between usual alcohol consumption and suicide mortality among men and women separately . in this study , estimates of relative risks associated with alcohol consumption variables  a one - drinking - day increase per week , a 70  g ( 5-drink ) increase of average alcohol intake per drinking day , and a 140  g ( 10-drink ) increase of average alcohol intake per week  were all higher in women , compared with men .
similar results have been observed in a previous study in korean adults , showing that women had a higher relative risk associated with moderate alcohol consumption ( 124  g / day ) , compared with men ( hr=1.83 , 95% ci 1.09 to 3.07 in women ; hr=1.20 , 95% ci 0.93 to 1.56 in men).6 p values of the interaction of sex were above 0.05 , partly due to the small number of suicide deaths .
however , given the lower body weight as well as the lower threshold of alcohol use for better cardiovascular health in women than in men , our findings may support a lower threshold in women than in men for interventions to prevent suicide death . in this study ,
relative risks associated with alcohol consumption - related continuous variables , unlike depressive symptoms,18 did not decrease during the latter half of follow - up ( 19972008 ) , compared with the first half ( 19851996 ) .
this finding was concordant with the previous findings in japanese men that relative risk of death by suicide associated with alcohol consumption did not decrease after exclusion of early follow - up.13 this finding suggests that alcohol consumption - related variables may be used as a risk stratification tool for a long - term suicide prevention programme .
a prospective design and nearly complete long - term follow - up on suicide using national mortality data are one of the strengths of this study .
a homogeneous study population with the same ethnicity and culture , who live in the same regional community , is another of its strengths .
yet another strength of our study is that it includes detailed information on alcohol consumption . to the best of our knowledge ,
only one prospective study examining the association with suicide death collected detailed information on alcohol consumption including drinking frequency , overall average consumption and quantity of alcohol consumed on drinking days.7 this study has limitations .
first , we observed only 61 suicide deaths , so statistical power may be lacking in some analyses , including the assessment of interaction by sex .
however , the number of suicides in persons with high alcohol consumption such as 30  g / day was comparable to studies with twice the number of all suicide deaths.5 
 7 
 12 second , our assessment of alcohol consumption was made using a self - reported questionnaire , and it was not validated separately .
however , self - report measures of alcohol consumption are known to have reasonable reliability and validity,19 and they were assessed prospectively before suicide death . therefore , potential measurement errors are most likely non - differential with respect to suicide death , and are unlikely to overestimate the risks .
third , depressive symptoms and other psychiatric disorders , strong predictors of suicide death , were not adjusted for.18 however , alcohol use status has been suggested to increase the risk of death by suicide , independently of other psychiatric disorders including depression.20 fourth , other potential confounders such as suicidal ideation , detailed information on health burden , social support and socioeconomic status were not included in the analysis .
fifth , our study could not distinguish between never drinkers and ex - drinkers among non - drinkers .
since ex - drinkers tended to have higher suicide mortality in some,11 
 18 but not all,13 previous studies , the risk of suicide death among current drinkers , compared with never drinkers , may be underestimated in this study .
sixth , suicide death was defined by death certificates . however , any misclassification of suicide , as mentioned earlier , is likely to have been mostly non - differential with regard to alcohol consumption ; thus , potential misclassifications generally would have been unlikely to overestimate the relative risk .
seventh , homogeneity of the participants could also be a limitation of our findings generalisability .
the magnitude of association of risk factors with suicide death may differ by ethnicity , culture , age and level of urbanicity.4 
 18 
 2124 therefore , some of our findings regarding the korean rural elderly individuals may have limited generalisability to other ethnic , cultural or age groups , or to urban populations .
few prospective cohort studies have ever examined the impact of the quantity of usual alcohol consumption on suicide mortality after adjustment for potential confounders.57 
 1113 
 17 among community - based cohort studies,1113 in 43  383 japanese men from a public health centre - based cohort , occasional drinkers had the lowest risk of death by suicide , while non - drinkers and heavy drinkers ( 414  g alcohol per week ) had a higher risk;11 in another public health centre - based cohort study in 22  804 japanese men ( mean age : 60  years ) , alcohol consumption was linearly associated with suicide death;13 in 128  934 participants of the northern california medical care programme in the usa , greater alcohol consumption ( especially 6 drinks per day ) was associated with higher suicide death.12 among occupation - based cohort studies,57 
 17 in around 49  000 norwegian conscripts , high alcohol consumption ( > 250  g / week ) was associated with a non - significantly increased risk of suicide ( hr=1.7 , 95% ci 1.0 to 2.8 ) compared to moderate consumption ( 1100  g / week);17 among 89  299 physicians and 47  654 health professionals in the usa , alcohol consumption was not associated with suicide death;5 
 7 among 1.3 million korean adults , mostly government and school employees , moderate alcohol intake ( 124  g / day ) , but not high alcohol intake ( 25  g / day ) , was associated with higher suicide mortality and alcohol intake was not linearly associated with suicide death.6 additionally , among nested case 
control studies based on prospective cohorts in the usa , the usual amount of alcohol consumption was not associated with suicide death in the community elderly aged 65  years and older , elderly in a retirement community and former college students.810 among prospective studies based on a community cohort , three studies examined the associations in the mainly elderly population with a mean age of 60  years or above.9 
 10 
 13 as noted in the previous paragraph , prospective studies have produced inconsistent results on the association between usual alcohol consumption and suicide death .
however , results from community - based cohort studies , including the current study , indicated that usual alcohol consumption may be linearly associated with suicide death in the community - dwelling population , at least among current drinkers.1113 additionally , our study does not support a protective effect of moderate alcohol consumption against suicide mortality in accordance with other,12 
 13 but not all,11 community - based cohort studies . as for occupation - based cohort studies ,
participants were mostly healthier , and had a higher socioeconomic status and potentially easier access to healthcare and other resources than the general population.57 they also had a generally lower alcohol consumption .
these factors combined might affect the association between usual alcohol intake and suicide mortality in previous occupation - based cohort studies .
prospective cohort studies have seldom evaluated the association between usual alcohol consumption and suicide mortality among men and women separately . in this study ,
estimates of relative risks associated with alcohol consumption variables  a one - drinking - day increase per week , a 70  g ( 5-drink ) increase of average alcohol intake per drinking day , and a 140  g ( 10-drink ) increase of average alcohol intake per week  were all higher in women , compared with men .
similar results have been observed in a previous study in korean adults , showing that women had a higher relative risk associated with moderate alcohol consumption ( 124  g / day ) , compared with men ( hr=1.83 , 95% ci 1.09 to 3.07 in women ; hr=1.20 , 95% ci 0.93 to 1.56 in men).6 p values of the interaction of sex were above 0.05 , partly due to the small number of suicide deaths .
however , given the lower body weight as well as the lower threshold of alcohol use for better cardiovascular health in women than in men , our findings may support a lower threshold in women than in men for interventions to prevent suicide death .
in this study , relative risks associated with alcohol consumption - related continuous variables , unlike depressive symptoms,18 did not decrease during the latter half of follow - up ( 19972008 ) , compared with the first half ( 19851996 ) .
this finding was concordant with the previous findings in japanese men that relative risk of death by suicide associated with alcohol consumption did not decrease after exclusion of early follow - up.13 this finding suggests that alcohol consumption - related variables may be used as a risk stratification tool for a long - term suicide prevention programme .
a prospective design and nearly complete long - term follow - up on suicide using national mortality data are one of the strengths of this study .
a homogeneous study population with the same ethnicity and culture , who live in the same regional community , is another of its strengths .
yet another strength of our study is that it includes detailed information on alcohol consumption . to the best of our knowledge ,
only one prospective study examining the association with suicide death collected detailed information on alcohol consumption including drinking frequency , overall average consumption and quantity of alcohol consumed on drinking days.7 this study has limitations .
first , we observed only 61 suicide deaths , so statistical power may be lacking in some analyses , including the assessment of interaction by sex .
however , the number of suicides in persons with high alcohol consumption such as 30  g / day was comparable to studies with twice the number of all suicide deaths.5 
 7 
 12 second , our assessment of alcohol consumption was made using a self - reported questionnaire , and it was not validated separately . however , self - report measures of alcohol consumption are known to have reasonable reliability and validity,19 and they were assessed prospectively before suicide death .
therefore , potential measurement errors are most likely non - differential with respect to suicide death , and are unlikely to overestimate the risks .
third , depressive symptoms and other psychiatric disorders , strong predictors of suicide death , were not adjusted for.18 however , alcohol use status has been suggested to increase the risk of death by suicide , independently of other psychiatric disorders including depression.20 fourth , other potential confounders such as suicidal ideation , detailed information on health burden , social support and socioeconomic status were not included in the analysis .
fifth , our study could not distinguish between never drinkers and ex - drinkers among non - drinkers .
since ex - drinkers tended to have higher suicide mortality in some,11 
 18 but not all,13 previous studies , the risk of suicide death among current drinkers , compared with never drinkers , may be underestimated in this study .
sixth , suicide death was defined by death certificates . however , any misclassification of suicide , as mentioned earlier , is likely to have been mostly non - differential with regard to alcohol consumption ; thus , potential misclassifications generally would have been unlikely to overestimate the relative risk .
seventh , homogeneity of the participants could also be a limitation of our findings generalisability .
the magnitude of association of risk factors with suicide death may differ by ethnicity , culture , age and level of urbanicity.4 
 18 
 2124 therefore , some of our findings regarding the korean rural elderly individuals may have limited generalisability to other ethnic , cultural or age groups , or to urban populations .
among the korean rural elderly , the frequency and amount of usual alcohol consumption , per drinking day and per week , had a linear dose  response relationship with suicide death .
when consuming alcohol with the same frequency and amount , compared with men , women might have a higher relative risk of suicide .
our findings suggest that there is no protective effect of moderate alcohol consumption on suicide death .
our results also support  the lower the better policy of alcohol intake , and a sex - specific alcohol threshold for any suicide prevention strategy implemented . 

what is already known on this subjectin a recent systematic review of the prospective studies , the magnitude of the association between alcohol use disorder and suicide death was moderate ( pooled risk ratio=1.74 , 95% ci 1.26 to 2.21).evidence that greater usual alcohol consumption is associated with higher suicide death in the prospective studies among the general population is inconclusive . 

what this study addsthe greater frequency and amount of usual alcohol consumption was linearly associated with higher suicide death , and there was no protective effect of moderate alcohol consumption against suicide death in the elderly persons in a rural community.when consuming alcohol with the same frequency and amount as men , women might have a higher relative risk of suicide . in a recent systematic review of the prospective studies ,
the magnitude of the association between alcohol use disorder and suicide death was moderate ( pooled risk ratio=1.74 , 95% ci 1.26 to 2.21 ) .
evidence that greater usual alcohol consumption is associated with higher suicide death in the prospective studies among the general population is inconclusive . the greater frequency and amount of usual alcohol consumption was linearly associated with higher suicide death , and there was no protective effect of moderate alcohol consumption against suicide death in the elderly persons in a rural community .
when consuming alcohol with the same frequency and amount as men , women might have a higher relative risk of suicide .
 backgroundthe evidence from prospective studies on whether greater usual alcohol consumption is associated with a higher risk of death by suicide in the general population is inconclusive.methods6163 participants ( 2635 men ; 3528 women ) in a 1985 survey among rural residents in korea aged 55  years and above were followed until 2008 . 
 a cox model was used to calculate hrs of suicide death after adjustment for demographic , socioeconomic and health - related confounders.results37 men and 24 women died by suicide . 
 elderly persons who consumed alcohol daily , 70  g alcohol ( 5 drinks ) or more per drinking day , or 210  g alcohol ( 15 drinks ) or more per week had higher suicide mortality ( p<0.05 ) , compared with non - drinkers . 
 an increase of one drinking day per week ( hr=1.17 , 95% ci 1.05 to 1.31 ) , 70  g ( 5 drinks ) additional alcohol intake per drinking day ( hr=1.38 , 95% ci 1.13 to 1.70 ) , and 140  g ( 10 drinks ) additional alcohol intake per week was associated with a 17% , 38% and 12% higher risk of suicide death , respectively . 
 women had a higher relative risk of suicide death associated with alcohol consumption , compared with men.conclusionsa greater frequency and amount of usual alcohol consumption was linearly associated with higher suicide death . 
 given the same amount of alcohol consumption , women might have a higher relative risk of suicide than men . 
 our findings support  the lower the better for alcohol intake , no protective effect of moderate alcohol consumption , and a sex - specific guideline ( lower alcohol threshold for women ) as actions to prevent suicide death . 
Introduction
Methods
Study population
Estimation of usual alcohol consumption
Baseline data collection
Follow-up and outcome assessment
Statistical analysis
Results
Discussion
Relationship to previous research
Association in women
Association according to follow-up time
Strengths and limitations of the study
Conclusion
Supplementary Material