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Incidence and factors associated with mortality in 2,476 patients with variant angina in Korea

View Article: PubMed Central - PubMed

ABSTRACT

This study investigated the incidence and risk factors of mortality in 2,476 patients with variant angina (VA) using the National Health Insurance Service–National Sample Cohort between 2004 and 2011. The risk factors of all-cause and cardiac mortality were investigated using Cox proportional hazards model. Most patients (69.5%) were less than 65 years and 42.9% were women. During the median follow-up duration of 4.9 years, there were 178 (7.2%) and 95 (3.8%) cases of all-cause and cardiac mortality, respectively. Older age, hypertension, diabetes mellitus, poor medication adherence, low household income and tertiary teaching hospitals were independent predictors for all-cause mortality, while older age, hypertension, low household income and tertiary teaching hospitals were independent predictors for cardiac mortality. In conclusion, our findings suggest that traditional risk factor control and continued medication are important to improve VA outcomes, and that household income-level factors should be considered in the assessment of risk of VA patients.

No MeSH data available.


Related in: MedlinePlus

Schematic representation of enrolment and follow-up of study subjects.*Number of new enrollees in each consecutive year from 2004 to 2011 applying at least 2 year to maximum 9 year washing out period. VA, variant angina; FU, follow-up.
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f2: Schematic representation of enrolment and follow-up of study subjects.*Number of new enrollees in each consecutive year from 2004 to 2011 applying at least 2 year to maximum 9 year washing out period. VA, variant angina; FU, follow-up.

Mentions: We used 2002–2013 data from NHIS-NSC, released by NHIS in 2014. This cohort data contains 1,025,340 people (as of 2002, approximately 2.2% of the entire Korean population) who were randomly selected for representing the entire Korean population33. In order to make randomized cohort samples, NHIS used probabilistic sampling to represent an individual’s total annual medical expenses within each of 1476 strata defined by age, sex, eligibility status (employed or self-employed), and income level (20 quartiles for each eligibility status and MA recipients) combinations via proportional allocation from the 46,605,433 Korean residents in 2002333637. In particular, NHIS-NSC was designed to be a semi-dynamically constructed cohort database; the cohort has been followed up to either the time of the participant’s disqualification from receiving health services due to death or emigration or until the end of the study period, whereas samples of newborn infants are included annually333637. The database contains eligibility and demographic information regarding NHI beneficiaries as well as data on MA recipients, medical bill details, medical treatment, disease histories, and prescriptions333637. NHIS-NSC data accessed in the current study included demographic information, including sex, age, residence regions, household income, and type of health security. In addition, inpatient and outpatient medical care utilization information for primary and subsidiary causes, including date of service, and drugs prescribed were included. The causes of medical care utilization or death were recorded under the International Classification of Diseases, 10th reversion (ICD-10). We included study subjects whose (1) primary cause of medical service usage was ‘I201 ’ or (2) subsidiary cause of ‘I201’ and cause of death of ‘I’, with no prior medical service usage under ‘I201’, either primary or subsidiary, before the time of inclusion in the study. For the onset of VA, we established 2002 to 2003 as the washing-out period, and excluded patients with any treatment or diagnosis history of VA during this period. To specifically detect new VA patients, we established a washing-out period from at least two years to nine years. Figure 2 shows the detailed information about how new enrollees were selected in each consecutive year from 2004 to 2011 after applying at least 2 year to maximum to 9 year washing out period. Using this model, enrollees in 2004 were the new onset VA patients with no prior diagnosis of VA during 2002–2003. (specifically, 267 enrollees in 2005 were new patients who were never diagnosed or treated for VA during 2002–2004 and 430 enrollees in 2011 were new patients with no record of VA during 2002–2010). Accordingly, patients with VA onset in 2004 would have a maximum follow up duration of nearly 10 years, and patients with VA onset in 2011 would have less follow up duration, but the duration would be >2 years. Follow-up for all VA patients was completed at the end of 2013 (Fig. 2).


Incidence and factors associated with mortality in 2,476 patients with variant angina in Korea
Schematic representation of enrolment and follow-up of study subjects.*Number of new enrollees in each consecutive year from 2004 to 2011 applying at least 2 year to maximum 9 year washing out period. VA, variant angina; FU, follow-up.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382575&req=5

f2: Schematic representation of enrolment and follow-up of study subjects.*Number of new enrollees in each consecutive year from 2004 to 2011 applying at least 2 year to maximum 9 year washing out period. VA, variant angina; FU, follow-up.
Mentions: We used 2002–2013 data from NHIS-NSC, released by NHIS in 2014. This cohort data contains 1,025,340 people (as of 2002, approximately 2.2% of the entire Korean population) who were randomly selected for representing the entire Korean population33. In order to make randomized cohort samples, NHIS used probabilistic sampling to represent an individual’s total annual medical expenses within each of 1476 strata defined by age, sex, eligibility status (employed or self-employed), and income level (20 quartiles for each eligibility status and MA recipients) combinations via proportional allocation from the 46,605,433 Korean residents in 2002333637. In particular, NHIS-NSC was designed to be a semi-dynamically constructed cohort database; the cohort has been followed up to either the time of the participant’s disqualification from receiving health services due to death or emigration or until the end of the study period, whereas samples of newborn infants are included annually333637. The database contains eligibility and demographic information regarding NHI beneficiaries as well as data on MA recipients, medical bill details, medical treatment, disease histories, and prescriptions333637. NHIS-NSC data accessed in the current study included demographic information, including sex, age, residence regions, household income, and type of health security. In addition, inpatient and outpatient medical care utilization information for primary and subsidiary causes, including date of service, and drugs prescribed were included. The causes of medical care utilization or death were recorded under the International Classification of Diseases, 10th reversion (ICD-10). We included study subjects whose (1) primary cause of medical service usage was ‘I201 ’ or (2) subsidiary cause of ‘I201’ and cause of death of ‘I’, with no prior medical service usage under ‘I201’, either primary or subsidiary, before the time of inclusion in the study. For the onset of VA, we established 2002 to 2003 as the washing-out period, and excluded patients with any treatment or diagnosis history of VA during this period. To specifically detect new VA patients, we established a washing-out period from at least two years to nine years. Figure 2 shows the detailed information about how new enrollees were selected in each consecutive year from 2004 to 2011 after applying at least 2 year to maximum to 9 year washing out period. Using this model, enrollees in 2004 were the new onset VA patients with no prior diagnosis of VA during 2002–2003. (specifically, 267 enrollees in 2005 were new patients who were never diagnosed or treated for VA during 2002–2004 and 430 enrollees in 2011 were new patients with no record of VA during 2002–2010). Accordingly, patients with VA onset in 2004 would have a maximum follow up duration of nearly 10 years, and patients with VA onset in 2011 would have less follow up duration, but the duration would be >2 years. Follow-up for all VA patients was completed at the end of 2013 (Fig. 2).

View Article: PubMed Central - PubMed

ABSTRACT

This study investigated the incidence and risk factors of mortality in 2,476 patients with variant angina (VA) using the National Health Insurance Service–National Sample Cohort between 2004 and 2011. The risk factors of all-cause and cardiac mortality were investigated using Cox proportional hazards model. Most patients (69.5%) were less than 65 years and 42.9% were women. During the median follow-up duration of 4.9 years, there were 178 (7.2%) and 95 (3.8%) cases of all-cause and cardiac mortality, respectively. Older age, hypertension, diabetes mellitus, poor medication adherence, low household income and tertiary teaching hospitals were independent predictors for all-cause mortality, while older age, hypertension, low household income and tertiary teaching hospitals were independent predictors for cardiac mortality. In conclusion, our findings suggest that traditional risk factor control and continued medication are important to improve VA outcomes, and that household income-level factors should be considered in the assessment of risk of VA patients.

No MeSH data available.


Related in: MedlinePlus