coronary heart disease ( chd ) is the second leading cause of death among chinese adults now - a - day .
health - related quality of life ( hrqol ) is useful for assessing the socio - economic impact and burden of illness , effectiveness of interventions and treatments , and long - term mortality among patients after a cardiac event .
so far , only a few studies assessed the hrqol of chinese chd patients , yielding inconsistent results .
the purpose of this study was to evaluate hrqol outcomes of chd patients in china using european quality of life 5-dimensions ( eq-5d ) questionnaire and identify important hrqol factors for this special population .
this was a cross - sectional study conducted from august to october , 2010 in rural communities of fangshan district , beijing , china , using a stratified cluster sampling technique .
eligible subjects are native residents aged 40 years or older living locally for at least 5 years , with a confirmed diagnosis of myocardial infarction or angina by a class - two or higher hospital with electrocardiography findings , or a surgical history of coronary revascularization , coronary artery bypass or coronary stent implantation .
subjects who were unable to answer the questionnaire and take part in physical examination personally were excluded .
all questionnaires were administered through personal interview , information collected on socio - demographic characteristics ( age , sex , marital status , educational level , the family 's population , household income per month ) , lifestyle factors ( physical activity , cigarette smoking and alcohol consumption ) and comorbidities , including hypertension , type 2 diabetes mellitus ( t2 dm ) and stroke .
marital status is divided into married and unmarried ( including single , divorced or widowed ) .
past smokers were those who had smoked more than 100 cigarettes in the past but had quit smoking during the last month .
current smokers were those who had smoked at least 100 cigarettes and had smoked during the last month .
past drinking was defined as consuming alcohol at least once a week in the past but not in the previous month .
current drinking was defined as drinking at least once per week and still drank at that frequency in the previous month .
the average daily intake of current drinkers was calculated by dividing the total weekly amount of pure alcohol by 7 days . according to the daily intake of alcohol , current drinkers
were categorized into four groups : low , moderate , high , and very high group ( for men 40 , 4160 , 61100 and > 100 g / d , for women 20 , 2140 , 4160 and > 60
physical activity was defined as performing physical exercise for at least 30 min at least once per week during the previous 6 months , not including housework or job - related work .
the frequency of physical activity was measured as : rarely / never , 14 times / week or 5 times / week .
household income per month ( in renminbi , rmb ) was classified as 3000 rmb or higher , 20002999 rmb , 15001999 rmb , and < 1500 rmb for first- to fourth - class rural areas , respectively .
classification for body mass index ( bmi ) was : underweight as bmi 18.5 , normal weight as bmi 18.524.9 , overweight as bmi 25.029.9 and obesity as bmi 30.0 .
subjects were defined as having hypertension if they were taking antihypertensive medications and/or having systolic blood pressure ( bp ) 140 mmhg , or diastolic bp 90 mmhg .
subjects were considered as having t2 dm if they had been diagnosed as t2 dm in hospitals , or self - reported current treatment with insulin or oral hypoglycemic drugs .
subjects were defined as having a stroke if they had a history of language or physical dysfunction continuing for more than 24 h and diagnosed using computerized tomography or magnetic resonance imaging .
body weight was measured without heavy clothes and shoes to the nearest 0.1 kg by a calibrated weighing scale and height was measured barefoot using a fixed stadiometer to the nearest 0.1 cm .
bmi is calculated as the ratio of weight to height squared ( kg / m ) .
health - related quality of life was measured by the eq-5d scales , developed by the euroqol group ( www.euroqol.org ) , well - validated and reliable in different cultures and various diseases including cardiac disease .
the eq-5d descriptive system consists of five dimensions of health on mobility , self - care , usual activities , pain / discomfort , and anxiety / depression .
each dimension has three levels of response ( no problems , moderate problems , and severe problems ) , level 1 ( no problems ) was coded as a  1  and level 2 ( moderate problems ) was coded as a  2  and level 3 ( severe problems ) was coded as a  3 .  for example , state 11111 indicates no problems on any of the 5 dimensions .
the eq-5d index score was generated by applying societal preference weights to each of the above five health dimensions according to a japan population - based time trade - off model and was calculated by adding up the weighted scores for all five dimensions .
european quality of life 5-dimensions also includes a separate 20 cm eq visual analog scale ( eq - vas ) to measure self - assessed health status .
respondents were asked to indicate how good or bad his / her own health state on the day of assessment on a 100-point scale , the end - points of which were labeled  best imaginable health state  and  worst imaginable health state  anchored at 100 and 0 ( rather like a thermometer ) , respectively .
this information can be used as a quantitative measure of health as judged by the individual respondents .
the compliance with drug treatment was evaluated in chd patients by the morisky - green test , which is a 4-item medication adherence questionnaire ( maq ) containing the following questions : ( 1 ) have you ever forgotten to take your medicines ? ( 2 ) were you careless at times about taking your medicines ? ( 3 ) when you felt better , did you sometimes stop taking your medicines ?
( 4 ) sometimes , if you felt worse , did you stop taking your medicines ?
score 1 for answering no to each of four questions and 0 for choosing yes .
score equal to four points means good compliance and score less than four points means poor compliance .
health quality was measured by eq-5d index and eq - vas scores and compared using one - way anova or t - test among groups defined by sex , age , education level , marital status , household income per month , family 's population , bmi , physical activity , smoking status , drinking status , comorbidities , compliance with drug treatment and the five dimensions of eq-5d .
the dimensions of eq-5d were dichotomized as  no problems  versus  moderate / severe problems . 
continuous variables were presented as the means with standard deviations , and categorical variables were presented as percentages .
stepwise multiple linear regression and unconditional logistic regression were used to explore the determinants of health quality using sex , age , education level , marital status , monthly household income , family 's population , bmi , physical activity , smoking status , alcohol drinking , comorbidities , compliance with drug treatment and duration of chd as independent variables .
odds ratios ( ors ) and 95% confidence intervals ( cis ) were obtained from logistic regression analysis .
analyses were performed using spss version 22.0 ( ibm corp . , armonk , ny , usa ) , a p < 0.05 as statistically significant .
this was a cross - sectional study conducted from august to october , 2010 in rural communities of fangshan district , beijing , china , using a stratified cluster sampling technique .
eligible subjects are native residents aged 40 years or older living locally for at least 5 years , with a confirmed diagnosis of myocardial infarction or angina by a class - two or higher hospital with electrocardiography findings , or a surgical history of coronary revascularization , coronary artery bypass or coronary stent implantation .
subjects who were unable to answer the questionnaire and take part in physical examination personally were excluded .
all questionnaires were administered through personal interview , information collected on socio - demographic characteristics ( age , sex , marital status , educational level , the family 's population , household income per month ) , lifestyle factors ( physical activity , cigarette smoking and alcohol consumption ) and comorbidities , including hypertension , type 2 diabetes mellitus ( t2 dm ) and stroke .
marital status is divided into married and unmarried ( including single , divorced or widowed ) .
past smokers were those who had smoked more than 100 cigarettes in the past but had quit smoking during the last month .
current smokers were those who had smoked at least 100 cigarettes and had smoked during the last month .
past drinking was defined as consuming alcohol at least once a week in the past but not in the previous month .
current drinking was defined as drinking at least once per week and still drank at that frequency in the previous month .
the average daily intake of current drinkers was calculated by dividing the total weekly amount of pure alcohol by 7 days .
according to the daily intake of alcohol , current drinkers were categorized into four groups : low , moderate , high , and very high group ( for men 40 , 4160 , 61100 and > 100 g / d , for women 20 , 2140 , 4160 and > 60
physical activity was defined as performing physical exercise for at least 30 min at least once per week during the previous 6 months , not including housework or job - related work .
the frequency of physical activity was measured as : rarely / never , 14 times / week or 5 times / week .
household income per month ( in renminbi , rmb ) was classified as 3000 rmb or higher , 20002999 rmb , 15001999 rmb , and < 1500 rmb for first- to fourth - class rural areas , respectively .
classification for body mass index ( bmi ) was : underweight as bmi 18.5 , normal weight as bmi 18.524.9 , overweight as bmi 25.029.9 and obesity as bmi 30.0 .
subjects were defined as having hypertension if they were taking antihypertensive medications and/or having systolic blood pressure ( bp ) 140 mmhg , or diastolic bp 90 mmhg .
subjects were considered as having t2 dm if they had been diagnosed as t2 dm in hospitals , or self - reported current treatment with insulin or oral hypoglycemic drugs .
subjects were defined as having a stroke if they had a history of language or physical dysfunction continuing for more than 24 h and diagnosed using computerized tomography or magnetic resonance imaging .
body weight was measured without heavy clothes and shoes to the nearest 0.1 kg by a calibrated weighing scale and height was measured barefoot using a fixed stadiometer to the nearest 0.1 cm .
bmi is calculated as the ratio of weight to height squared ( kg / m ) .
health - related quality of life was measured by the eq-5d scales , developed by the euroqol group ( www.euroqol.org ) , well - validated and reliable in different cultures and various diseases including cardiac disease .
the eq-5d descriptive system consists of five dimensions of health on mobility , self - care , usual activities , pain / discomfort , and anxiety / depression .
each dimension has three levels of response ( no problems , moderate problems , and severe problems ) , level 1 ( no problems ) was coded as a  1  and level 2 ( moderate problems ) was coded as a  2  and level 3 ( severe problems ) was coded as a  3 .
 for example , state 11111 indicates no problems on any of the 5 dimensions .
the eq-5d index score was generated by applying societal preference weights to each of the above five health dimensions according to a japan population - based time trade - off model and was calculated by adding up the weighted scores for all five dimensions .
european quality of life 5-dimensions also includes a separate 20 cm eq visual analog scale ( eq - vas ) to measure self - assessed health status .
respondents were asked to indicate how good or bad his / her own health state on the day of assessment on a 100-point scale , the end - points of which were labeled  best imaginable health state  and  worst imaginable health state  anchored at 100 and 0 ( rather like a thermometer ) , respectively .
this information can be used as a quantitative measure of health as judged by the individual respondents .
the compliance with drug treatment was evaluated in chd patients by the morisky - green test , which is a 4-item medication adherence questionnaire ( maq ) containing the following questions : ( 1 ) have you ever forgotten to take your medicines ? ( 2 ) were you careless at times about taking your medicines ? ( 3 ) when you felt better , did you sometimes stop taking your medicines ? ( 4 ) sometimes , if you felt worse , did you stop taking your medicines ?
score 1 for answering no to each of four questions and 0 for choosing yes .
score equal to four points means good compliance and score less than four points means poor compliance .
health quality was measured by eq-5d index and eq - vas scores and compared using one - way anova or t - test among groups defined by sex , age , education level , marital status , household income per month , family 's population , bmi , physical activity , smoking status , drinking status , comorbidities , compliance with drug treatment and the five dimensions of eq-5d .
the dimensions of eq-5d were dichotomized as  no problems  versus  moderate / severe problems . 
continuous variables were presented as the means with standard deviations , and categorical variables were presented as percentages .
stepwise multiple linear regression and unconditional logistic regression were used to explore the determinants of health quality using sex , age , education level , marital status , monthly household income , family 's population , bmi , physical activity , smoking status , alcohol drinking , comorbidities , compliance with drug treatment and duration of chd as independent variables .
odds ratios ( ors ) and 95% confidence intervals ( cis ) were obtained from logistic regression analysis .
, armonk , ny , usa ) , a p < 0.05 as statistically significant .
there were 1989 eligible chd patients , of whom 1928 completed the questionnaires , aged 4088 ( mean age 61.64  9.24 ) years , 29.4% men and 70.6% women , and were enrolled for further analysis , with a response rate of 96.9% .
duration of chd ranged from 1 to 44 ( median 3 , 2575 percentiles 27 ) years .
the mean score of eq-5d index was 0.889  0.172 , eq - vas score 71.56  17.65 . among the five domains of hrqol , anxiety / depression problem occurred in the lowest proportion of 7.9% patients , whereas pain / discomfort problem took the largest proportion of 24.3% .
study variables and the hrqol scores of chd subjects were presented and compared as shown in table 1 . although sex , comorbidity of hypertension , and compliance with drug treatment had no association with either eq-5d index or eq - vas scores ( p > 0.05 ) , significant associations were observed among other demographic and related variables ( p < 0.05 ) .
relationship between study variables and hrqol of chd patients * p<0.05 ; p<0.01 ; p<0.001 .
bmi : body mass index ; hrqol : health - related quality of life ; chd : coronary heart disease ; eq-5d : european quality of life 5-dimensions ; sd : standard deviation ; eq - vas : european quality of life visual analog scale .
multiple linear regression results in table 2 show that older age and stroke were negatively associated with a low eq-5d index .
physical activity , household income per month , alcohol drinking , and family 's population were positively related to high eq-5d index .
being married , physical activity , alcohol drinking , and family 's population were positively relevant with improving eq - vas scores .
stepwise multiple linear regression analysis for the determinants of hrqol in chd patients * p<0.05 ; p<0.01 ; p<0.001 .
b : standard error of regression coefficient ; hrqol : health - related quality of life ; chd : coronary heart disease ; eq - vas : european quality of life visual analog scale ; eq-5d : european quality of life 5-dimensions .
logistic regression was performed for the five dimensions of eq-5d to determine dimension - specific factors related to hrqol .
ors , 95% ci and p values are presented in table 3 . compared to patients of age
< 50 years , patients of age 80 years had more problems in mobility ( or = 3.236 ) , usual activities ( or = 3.440 ) , pain / discomfort ( or = 2.802 ) , and anxiety / depression ( or = 6.935 ) .
patients aged 7079 years met with more problems in usual activities ( or = 2.151 ) , whereas patients of 5059 or 6069 years experienced more problems in anxiety / depression ( or = 2.934 and or = 3.379 , respectively ) .
compared to patients with normal weight , obese patients ( bmi 30 kg / m ) had more problems in mobility ( or = 1.632 ) and pain / discomfort ( or = 1.633 ) , whereas underweight patients ( bmi 18.5 kg / m ) had more problems in pain / discomfort ( or = 2.431 ) .
patients with stroke were more likely to exhibit problems in self - care ( or = 2.121 ) , usual activities ( or = 1.976 ) and mobility ( or = 1.465 ) , whereas patients with diabetes mellitus were more likely to have problems in anxiety / depression ( or = 1.774 ) .
physical activity had positive effects on mobility ( 14 times / week : or = 0.462 ; 5 times / week : or = 0.495 ) , self - care ( 14 times / week : or = 0.457 ; 5 times / week : or = 0.354 ) , usual activities ( 14 times / week : or = 0.332 ; 5 times / week : or = 0.475 ) and pain / discomfort ( 14 times / week : or = 0.517 ; 5 times / week : or = 0.760 ) .
patients living with 2 , 35 or > 6 family members experienced less problems in mobility ( or = 0.505 , or = 0.318 and or = 0.424 , respectively ) .
past smoking had negative effects on mobility ( or = 1.983 ) , self - care ( or = 2.592 ) , usual activities ( or = 2.613 ) and pain / discomfort ( or = 1.971 ) .
low- , medium- , and high - alcohol drinking were associated with less problems in mobility ( or = 0.373 , or = 0.286 and or = 0.097 , respectively ) .
past and medium alcohol drinkers had less problems in self - care ( or = 0.276 and or = 0.193 , respectively ) .
high education level was protective factors for self - care ( or = 0.575 ) . compared to patients with monthly household income < 1500 rmb ,
patients with 20002999 or 3000 rmb reported less problems in usual activities ( or = 0.505 and or = 0.430 , respectively ) , those with 20002999 rmb suffering less pain / discomfort ( or = 0.544 ) . logistic regression analysis for dimension - specific factors related to hrqol in chd patients
hrqol : health - related quality of life ; chd : coronary heart disease ; bmi : body mass index ; or : odds ratio ; ci : confidence interval .
several studies indicated that smoking , increasing age , lower education level , less household income , and comorbid stroke or diabetes mellitus were related to deteriorated hrqol of chd patients , which was similar to our study .
this is inconsistent with previous studies which showed worse hrqol of female chd patients compared to male patients and may be partly due to a skewed sex ratio ( male 29.4% , female 70.6% ) in our study population , as a result of most skilled men working away in other cities , which is a common phenomenon in rural china .
so far , the relationship between bmi and quality of life in patients with chd has not been particularly well - illustrated .
several studies have shown that being overweight or obese ( bmi 25 kg / m ) was associated with greater survival in coronary artery disease patients compared to normal or  ideal 
kg / m ) had more problems in mobility ( or = 1.632 , p = 0.014 ) and pain / discomfort ( or = 1.633 , p = 0.006 ) , similar to previous reports which suggested that hrqol was impaired in chd patients with obesity compared to patients with a normal bmi .
our results also indicated that underweight patients ( bmi 18.5 kg / m ) reported more problems in pain / discomfort ( or = 2.431 , p = 0.022 ) and exhibited the worst eq-5d index in comparison to normal and overweight patients .
this discrepancy may be attributed to different body composition among the study population , as well as effects of body fat and fat - free mass on hrqol .
previous studies have demonstrated a j- or u - shaped association between alcohol drinking and the risk of chd . however , not all the studies replicated such type of association . in our study , certain alcohol drinking was related to better hrqol , as patients with medium or high drinking had less problems in mobility , self - care and usual activities , consistent with previous reports .
a recent study revealed that moderate alcohol intake related to improved hdl - cholesterol , fibrinogen and markers of glucose metabolism , implicating reduced chd risk of moderate drinkers .
heavy and binge drinking were also associated with favorable levels of chd biomarkers , and this may be a possible explanation for the negative relationship between alcohol drinking and chd risk .
first , the study used a cross - sectional design and could not show the effects of changes in demographic and related factors over time on hrqol and provide causal information .
we focused on the quality of life of chd patients and a control group without chd was not included .
second , because of data availability , we were unable to obtain treatments received for chd , cardiac function , revascularization method and other clinical factors that may influence hrqol .
third , there are more women than men in our study and selection bias may occur since generally men are affected more by chd than women .
the strength of our study lies in its focus on the hrqol of chd patients in china and was carried out in representative residents of the rural northern han chinese .
our data will be useful for future research in this field , and may provide more valuable information on hrqol in patients with chd when combined with other questionnaires , for example , questionnaires of seattle angina questionnaire , social support scale , and self - rating depression scale . in summary
, this study suggests that older age , comorbid diabetes mellitus and stroke , obesity , underweight , less income , living alone , smoking , less physical activity , and lower education level are negative correlates of impairment of hrqol in chd patients . being married , having more physical activity , moderate alcohol drinking and big family are protective factors for hrqol in chd patients .
clinicians could pay more attention to chd patients with these characteristics so as to optimize care and improve quality of life in this special population .
further large - scale cohort studies should be conducted to confirm our results in the future .
 background : although coronary heart disease ( chd ) is one of the major cardiovascular diseases , risk factors associated with the health - related quality of life ( hrqol ) of chd patients remain unclear . 
 the present study was designed to determine the profile and significant factors of the hrqol in chd patients.methods:a cross - sectional study was conducted in rural communities of fangshan district , beijing , china . socio - demographic , lifestyle , and comorbidity information of chd patients 
 were collected by a structured questionnaire and medical records . 
 hrqol was measured using european quality of life 5-dimensions ( eq-5d ) scale and eq visual analog scale ( eq - vas ) . 
 multiple linear and logistic regressions were performed to explore the association of potential risk factors with hrqol scores and each eq-5d , respectively.results:totally , 1928 chd patients ( mean age 61.64  9.24 years ; female : male = 2.4:1 ) were enrolled in the study . 
 the mean score of eq-5d index and eq - vas were 0.889  0.172 and 71.56  17.65 , respectively . 
 multiple linear regression revealed that marital status , physical activity , moderate alcohol drinking , and family 's population were positive independent correlates of eq - vas , whereas diabetes mellitus and stroke were negative independent correlates ( all p < 0.05 ) . 
 age and stroke were negatively while physical activity , moderate alcohol drinking , family 's population and household income were positively correlated with eq-5d index ( all p < 0.05 ) independently . 
 in addition , each of the five hrqol dimensions had various specific determinants , including obesity , underweight , smoking or education.conclusions:findings of the study highlight certain socio - demographic , lifestyle factors , and comorbid stroke or diabetes mellitus as correlates of hrqol in chinese chd patients . 
 large - scale cohort studies should be carried out to confirm our results in the future . 
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