Framingham risk prediction equations for incidence of cardiovascular disease using detailed measures for smoking

The incremental predictive value of arterial stiffness over SCORE2 in the setting of primary cardiovascular prevention: a 6-year follow-up study

AIM

Arterial stiffness hallmarks age-related cardiovascular diseases, precedes their onset and strongly links to accelerated disease progression. However, whether carotid-to-femoral pulse wave velocity (PWV), a proxy of arterial stiffness, predicts cardiovascular risk over and above SCORE2, a newly introduced risk score remains to be investigated.

METHODS

We measured PWV among 747 individuals without established atheromatosis. Study participants were followed up over a 6-year period for the incidence of cardiovascular events [[MACE)-cardiovascular mortality, stroke and myocardial infarction].

RESULTS

PWV emerged as an independent and additive predictor of first cardiovascular events when added in a model encompassing SCORE2 (hazard ratio = 1.10; 95% confidence interval (95% CI) = 1.07-1.14; P  < 0.001, Brier score changed from 0.073 (0.060-0.086) to 0.067 (0.055-0.081); P  < 0.001, c-statistic increased from 0.71 to 0.75; P  = 0.017; likelihood ratio: 20.22; P  < 0.001; the overall net reclassification improvement (NRI): 0.577; P  < 0.001, AICc changed from 697.81 to 679.60; BIC changed from 702.42 to 688.82]. An increase in PWV predicted a greater risk of future MACEs additively to conventional risk factors ( P  < 0.05). We performed Kaplan-Meier survival analysis for the tertiles of PWV [first tertile < 8.04 m/s; the second tertile: (8.04-10 m/s); the third tertile: (10-17.10 m/s); ( P  < 0.05 for all comparisons between the tertiles). PWV tertiles also predicted MACE when added to SCORE2 [for the second tertile: hazard ratio: 5.87 (95% CI: 1.73-19.92); P  = 0.004 and for the third tertile: hazard ratio: 9.69 (95% CI: 2.97-31.55); P  < 0.001 with the respective change of c-statistic from 0.739 to 0.772; P  = 0.012 and continuous NRI = 0.598].

CONCLUSION

PWV confers additive prognostic value to the newly introduced SCORE2 for adverse outcome in primary prevention.

Predicting incident cardiovascular disease among African-American adults: A deep learning approach to evaluate social determinants of health in the Jackson heart study

The present study sought to leverage machine learning approaches to determine whether social determinants of health improve prediction of incident cardiovascular disease (CVD). Participants in the Jackson Heart study with no history of CVD at baseline were followed over a 10-year period to determine first CVD events (i.e., coronary heart disease, stroke, heart failure). Three modeling algorithms (i.e., Deep Neural Network, Random Survival Forest, Penalized Cox Proportional Hazards) were used to evaluate three feature sets (i.e., demographics and standard/biobehavioral CVD risk factors [FS1], FS1 combined with psychosocial and socioeconomic CVD risk factors [FS2], and FS2 combined with environmental features [FS3]) as predictors of 10-year CVD risk. Contrary to hypothesis, overall predictive accuracy did not improve when adding social determinants of health. However, social determinants of health comprised eight of the top 15 predictors of first CVD events. The social determinates of health indicators included four socioeconomic factors (insurance status and types), one psychosocial factor (discrimination burden), and three environmental factors (density of outdoor physical activity resources, including instructional and water activities; modified retail food environment index excluding alcohol; and favorable food stores). Findings suggest that whereas understanding biological determinants may identify who is currently at risk for developing CVD and in need of secondary prevention, understanding upstream social determinants of CVD risk could guide primary prevention efforts by identifying where and how policy and community-level interventions could be targeted to facilitate changes in individual health behaviors.

Impaired Endothelial Glycocalyx Predicts Adverse Outcome in Subjects Without Overt Cardiovascular Disease: a 6-Year Follow-up Study

We investigated whether disturbance of glycocalyx integrity is related with increased cardiovascular risk. In 600 healthy subjects, we measured perfused boundary region (PBR), a marker of glycocalyx integrity, in sublingual microvessels with diameter ranging 5-25 µm using a dedicated camera (Sideview Darkfield Imaging). Increased PBR indicates reduced glycocalyx thickness. We prospectively monitored the occurrence of cardiovascular events (MACE-death, myocardial infarction, and stroke) during a 6-year follow-up. Fifty-seven MACE were documented. Increased values of PBR5-25 predicted higher risk for MACE in a model including sex, age, hyperlipidemia, diabetes, hypertension, smoking, family history of coronary disease, treatment with ACEi/ARBs, or lipid-lowering agents (hazard ratio (HR), 6.44, p = 0.011; net reclassification improvement (NRI), 28%; C-statistic: 0.761). PBR5-25 was an independent and additive predictor of outcome when added in a model including the European Heart SCORE, diabetes, family history of CAD, and medication (HR, 4.71; NRI: 39.7%, C-statistic from 0.653 to 0.693; p < 0.01).Glycocalyx integrity is an independent and additive predictor to risk factors for MACE at 6-year follow-up in individuals without cardiovascular disease. ClinicalTrials.govIdentifier:NCT04646252. PBR5-25 was an independent and additive predictor of adverse cardiovascular events in a model including the European Heart SCORE, diabetes, family history of coronary disease, and medication (HR: 4.71, NRI: 39.7%, C-statistic from 0.653 to 0.693; p < 0.01, NRI:37.9%).

A cross country comparison for the burden of cardiovascular disease attributable to tobacco exposure in China, Japan, USA and world

BACKGROUND

Tobacco exposure (TE) is the major contributor for CVD mortality, but few published studies on CVD mortality attributable to TE have analyzed the potential reasons underlying long-term trends in China. Our studysought to find the potential reasons and compared CVD mortality attributable to TE in China, Japan, the United States of America (USA), and the world between 1990 and 2017.

METHODS

The mortality data in China, Japan, the USA, and the world were obtained from Global Burden of Disease Study 2017(GBD 2017). Joinpoint regression was used to assess the trend magnitude and directions over time for CVD mortality, while the age-period-cohort method was used to analyzethe temporal trends of CVD mortality according to age, period, and cohort.

RESULTS

A significant downward trend was found in the age-standardised mortality rate (ASMR) of CVD attributable to smoking in four regions. China had the smallest decline and the Chinese ASMR became the highest in 2017. All the annual net drifts in the four regions were negative and the local drifts were below zero. The longitudinal age curves of CVD mortality attributable to smoking increased in four regions,with China having the largest increase. The period or cohort RRs indicated a decline, and China had the smallest decline. The researchers further analyzed the IHD and stroke trends, finding that the morality and period or cohort RR of IHD in China was always at a high level.

CONCLUSIONS

CVD mortality attributable to TE declined in four regions, and was highest in China. The proportion of IHD mortality attributable to TE was similar to stroke, which significantly changed the traditional cognition of CVD composition, but the control measure was not sufficient for IHD in China.

Sublingual endothelial glycocalyx and atherosclerosis. A cross-sectional study

Background

Damage to endothelial glycocalyx is thought to be an early marker of atherosclerosis and measuring reduced glycocalyx size clinically via the Perfused Boundary Region (PBR) may allow early detection of cardiovascular disease. However, the true value of the glycocalyx in estimating cardiovascular risk or detecting cardiovascular disease is uncertain. We therefore investigated whether small glycocalyx size is associated with cardiovascular risk or disease in a large multi-ethnic cohort.

Methods

In a multi-ethnic community-based sample (N = 6169, 42.4% male, mean age 43.6 ±13) we applied multiple imputation for missing data and used logistic regression and odds ratios to cross-sectionally investigate the relationship of small glycocalyx size as estimated by highest quartile of PBR with, on the one hand, classical risk factors for atherosclerosis including age, sex, diastolic and systolic blood pressure, LDL, HDL, triglycerides, BMI, diabetes, smoking status, and antihypertensive and lipid-lowering medication; on the other hand, prevalent cardiovascular disease. Analyses were additionally adjusted for ethnicity.

Results

With PBR divided in quartiles, the highest PBR quartile (smallest glycocalyx size) as dependent variable was independently associated with female sex (OR for male versus female: 0.61, 95% CI: 0.53, 0.70) and diabetes (OR: 1.28, 95% CI: 1.03–1.59) in a model adjusted for all classical risk factors of atherosclerosis and for ethnicity. With regard to cardiovascular disease, no association was found between the smallest glycocalyx size as independent variable and overall cardiovascular disease, coronary heart disease and revascularization procedures, or stroke.

Conclusions

Small glycocalyx size as estimated by highest PBR is associated with female sex and diabetes, which do not completely reflect a high cardiovascular risk profile. At the same time, glycocalyx size is not associated with prevalent cardiovascular disease.

Effect of present versus previous smoking on non-invasive haemodynamics

We examined cardiovascular function in 637 volunteers (19-72 years) without antihypertensive medication in never smokers (n = 365), present smokers (n = 81) and previous smokers (n = 191, median abstinence 10 years). Haemodynamics during passive head-up tilt were recorded using whole-body impedance cardiography and radial pulse wave analysis. Results were adjusted for age, sex, body mass index, LDL cholesterol and alcohol use. Systolic and diastolic blood pressure, heart rate, and pulse wave velocity were not different between the groups. Supine aortic reflection times did not differ, while upright values were shorter in present versus previous smokers (p = 0.04). Heart rate adjusted augmentation index was increased in the supine position in present smokers versus controls (p = 0.045), and in present (p < 0.001) and previous (p = 0.031) smokers versus controls in the upright position. Supine and upright cardiac output was higher (p ≤ 0.016) and systemic vascular resistance lower (p ≤ 0.001) in present versus previous smokers. In spite of the long abstinence, in the upright position previous smokers had lower cardiac output (p = 0.032) and higher systemic vascular resistance (p = 0.014) than never smokers. In the absence of differences in blood pressure and arterial stiffness, present smokers presented with hyperdynamic circulation and enhanced wave reflection compared with previous smokers.

Association of Family History With Cardiovascular Disease in Hypertensive Individuals in a Multiethnic Population

BACKGROUND

Hypertension alone is a poor predictor of the individual risk of cardiovascular disease. Hereditary factors of which hypertension is merely a marker may explain why some hypertensive individuals appear more susceptible to cardiovascular disease, and why some ethnicities have more often seemingly hypertension-related cardiovascular disease than others. We hypothesize that, in hypertensive individuals, a positive family history of cardiovascular disease identifies a high-risk subpopulation.

METHODS AND RESULTS

Healthy Life in Urban Settings (HELIUS) is a cohort study among participants of Dutch, South-Asian Surinamese, African Surinamese, Ghanaian, Turkish, and Moroccan origin aged 70 years and younger. In participants with hypertension (n=6467), we used logistic regression to assess the association of family history of cardiovascular disease with prevalent stroke and nonstroke cardiovascular disease, adjusting for sex, age, education, and smoking. To detect ethnic differences, we tested for interaction between family history and ethnicity and stratified the analysis by ethnicity. A positive family history was associated with a higher prevalence of nonstroke cardiovascular disease (odds ratio [OR], 2.05; 95% CI, 1.65-2.54) and stroke (OR, 1.62; 95% CI, 1.19-2.20). The strongest association of family history with nonstroke cardiovascular disease was found among the Dutch (OR, 2.47; 95% CI, 1.37-4.44) and with stroke among the African Surinamese (OR, 2.17; 95% CI, 1.32-3.57). The interaction between family history and African Surinamese origin for stroke was statistically significant.

CONCLUSIONS

In multiethnic populations of hypertensive patients, a positive family history of cardiovascular disease may be used clinically to identify individuals at high risk for nonstroke cardiovascular disease regardless of ethnic origin and African Surinamese individuals at high risk for stroke.

Smoking intensity (pack/day) is a better measure than pack-years or smoking status for modeling cardiovascular disease outcomes

OBJECTIVES

Smoking as an epidemiological exposure can be quantified in many ways including duration, intensity, pack-years, recency, and age at initiation. However, it is not clear which of these are most important for cardiovascular disease (CVD) and how they should be modeled.

STUDY DESIGN AND SETTING

Using the Multi-Ethnic Study of Atherosclerosis, Cox models for time to incident CVD adjusted for age, sex, race/ethnicity, education category, and income category were compared which included various characterizations of smoking history.

RESULTS

Duration, age at starting, time since quitting, and noncigarette forms of smoking were not independently associated with CVD, whereas baseline current intensity was associated with CVD [e.g., hard CVD hazard ratio 1 pack/d of 1.85 95% confidence interval (1.33, 2.57)]. Former smokers, regardless of duration, intensity, or recency, were not at increased risk, suggesting that risk may risk may drop precipitously from the time of quitting. For CVD events, representing smoking exposure as baseline smoking intensity produced better model fit as measured by Akaike information criterion than models using smoking status or pack-years.

CONCLUSION

The association of smoking with incident CVD events was well captured by including a simple term for baseline smoking intensity.

Cardiovascular disease risk factors in relation to smoking behaviour and history: a population-based cohort study

Objective

To investigate how individual risk factors for cardiovascular disease (CVD) (blood pressure, lipid levels, body mass index, waist and hip circumference, use of antihypertensive or hypolipidemic medication, and diagnosed diabetes) differ in people aged 46 years with different smoking behaviour and history.

Methods

This population-based cohort study is based on longitudinal data from the Northern Finland Birth Cohort 1966 project. Data were collected at the 31-year and 46-year follow-ups, when a total of 5038 and 5974 individuals participated in clinical examinations and questionnaires. Data from both follow-ups were available for 3548 participants. In addition to individual CVD risk factors, Framingham and Systematic Coronary Risk Evaluation (SCORE) algorithms were used to assess the absolute risk of a CVD event within the next decade.

Results

The differences in individual risk factors for CVD reached statistical significance for some groups, but the differences were not consistent or clinically significant. There were no clinically significant differences in CVD risk as measured by Framingham or SCORE algorithms between never smokers, recent quitters and former smokers (7.5%, 7.4%, 8.1% for men; 3.3%, 3.0%, 3.2% for women; p<0.001).

Conclusions

The effect of past or present smoking on individual CVD risk parameters such as blood pressure and cholesterol seems to be of clinically minor significance in people aged 46 years. In other words, smoking seems to be above all an independent risk factor for CVD in the working-age population. Quitting smoking in working age may thus reduce calculated CVD risk nearly to the same level with people who have never smoked.

Cardiovascular risk factors among industrial workers: a cross-sectional study from eastern Nepal

BACKGROUND

Cardiovascular diseases (CVD) are the number one cause of death globally, more people die annually from CVDs than from any other cause. An estimated 17.5 million people died from CVD in 2012, representing 46.2 % of all NCD death globally. An accurate characteristic of the cardiovascular risk factors in a specified population group is essential for the implementation of educational campaign. However, there are no reliable CVD risk factors burden, nor of its awareness and treatment status in Nepal industrial settings. We aimed to assess cardiovascular risk factors among men age 20-59 years in one of the largest industrial corridor of Eastern Nepal.

METHODS

A total of 494 industrial workers between ages of 20-59 years, from two industries participated in the study. Pretested semi-structured questionnaire was used to collect the information. Primary outcome was cardiovascular risk factors based on STEPS survey and study on non-communicable disease in Nepal. A semi-structured questionnaire was used to interview 494 industrial workers. Lipid profile and serum blood glucose of 406 workers and electrocardiogram of 400 workers was done.

RESULTS

The prevalence of cardiovascular disease (CVD) was 13.8 %. Those who were >45 years were 2.72 times more likely to develop CVD. Those who smoked more pack year, had family history of hypertension (HTN) and consumed no fruits were 4.32, 1.90.2.47 times more likely to develop CVD. Low density Lipoprotein (LDL) level <130 was found to be protective compared to LDL level above ≥ 130. On adjusted analysis those who did not consume fruits and had high LDL level were 3.32 and 3.03 more likely to develop CVD.

CONCLUSION

There is high prevalence of CVD risk factors. Although majority of them are literate there is lack of health education and awareness among young male population in an eastern Nepal industrial setting.

Understanding adherence to medications in type 2 diabetes care and clinical trials to overcome barriers: a narrative review

AIM

To identify factors affecting adherence to medications in type 2 diabetes (T2D) care and clinical trials.

BACKGROUND

Adherence to medication is associated with better patient outcomes, lower healthcare costs, and improved quality and robustness of trial data. In T2D, non-adherence to regimens may compromise glycemic, blood pressure and lipid control, which can, in turn, increase morbidity and mortality rates.

DESIGN

A literature search was performed to identify studies reporting adherence to medications and highlighting specific adherence challenges/approaches in T2D. The search was limited to clinical trials, comparative studies or meta-analyses, reported in English with a freely available abstract.

DATA SOURCE

MEDLINE (31 December 2008 to 31 December 2013).

REVIEW METHODS

Studies not reporting adherence to medications or highlighting adherence challenges/approaches in T2D, presenting only self-reported adherence or including fewer than 100 patients were excluded. Eligible reports are discussed narratively.

RESULTS

Factors identified as having a detrimental impact on adherence were smoking, depression and polypharmacy. Conversely, increased convenience (e.g. pen compared with vial and syringe; medication supplied by mail order vs. retail pharmacy) was associated with better patient adherence, as were interventions that increased patient motivation (e.g. individualized, nurse-led consultation) and education.

CONCLUSIONS

Medication adherence is influenced by complex and multifactorial issues, which can include smoking, depression, polypharmacy, convenience of obtaining and administering the medication, patient motivation and education. We recommend simplifying treatment regimens, where possible, improving provider-patient communication, and providing support and education to increase medication adherence, with a view to improving patient outcomes and clinical trial data quality.

Long-term smoking cessation and heart rate dynamics in an aging healthy cohort: Is it possible to fully recover?

AIM

To evaluate the long-term influence of smoking cessation on the regulation of the autonomic cardiovascular system in an aging general population, using the subpopulation of lifelong non-smokers as control group.

METHODS

We analyzed 1481 participants aged ≥50 years from the SAPALDIA cohort. In each participant, heart rate variability and heart rate dynamics were characterized by means of various quantitative analyzes of the inter-beat interval time series generated from 24-hour electrocardiogram recordings. Each parameter obtained was then used as the outcome variable in multivariable linear regression models in order to evaluate the association with smoking status and time elapsed since smoking cessation. The models were adjusted for known confounding factors and stratified by the time elapsed since smoking cessation.

RESULTS

Our findings indicate that smoking triggers adverse changes in the regulation of the cardiovascular system, even at low levels of exposure since current light smokers exhibited significant changes as compared to lifelong non-smokers. Moreover, there was evidence for a dose-response effect. Indeed, the changes observed in current heavy smokers were more marked as compared to current light smokers. Furthermore, full recovery was achieved in former smokers (i.e., normalization to the level of lifelong non-smokers). However, while light smokers fully recovered within the 15 first years of cessation, heavy former smokers might need up to 15-25 years to fully recover.

CONCLUSION

This study supports the substantial benefits of smoking cessation, but also warns of important long-term alterations caused by heavy smoking.

Prevalence of self-reported myocardial infarction in Sami and non-Sami populations: the SAMINOR study

Objective

Measure the prevalence of self-reported myocardial infarction (SMI) in Sami and non-Sami populations in rural areas of Norway, and explore whether possible ethnic differences could be explained by established cardiovascular risk factors.

Design

Cross-sectional population-based study.

Methods

A health survey was conducted in 2003–2004 in areas with Sami and non-Sami populations (SAMINOR). The response rate was 60.9%. Information concerning lifestyle was collected by 2 self-administrated questionnaires, and clinical examinations provided anthropometric measurements, and data on blood pressure and lipid levels.

Results

The total number for the subsequent analysis was 15,206 men and women aged 36–79 years (born 1925–1968). Sex-specific analyses revealed no ethnic difference in SMI. In terms of the most important risk factors such as smoking, blood pressure, and lipid levels, no or only trivial ethnic differences were found in both women and men.

Conclusion

In this study, we found no difference in SMI between Sami and non-Sami in rural areas in Norway. The similar risk profile is the most plausible explanation; similar living conditions and close interaction between the ethnic groups may explain this.

Ethnic difference in the prevalence of angina pectoris in Sami and non-Sami populations: the SAMINOR study

Objective

To assess the population burden of angina pectoris symptoms (APS), self-reported angina and a combination of these, and explore potential ethnic disparity in their patterns. If differences in APS were found between Sami and non-Sami populations, we aimed at evaluating the role of established cardiovascular risk factors as mediating factors.

Design

Cross-sectional population-based study.

Methods

A health survey was conducted in 2003–2004 in areas with Sami and non-Sami populations (SAMINOR). The response rate was 60.9%. The total number for the subsequent analysis was 15,206 men and women aged 36–79 years (born 1925–1968). Information concerning lifestyle was collected by 2 self-administrated questionnaires, and clinical examinations provided data on waist circumference, blood pressure and lipid levels.

Results

This study revealed an excess of APS, self-reported angina and a combination of these in Sami relative to non-Sami women and men. After controlling for age, the odds ratio (OR) for APS was 1.42 (p<0.001) in Sami women and 1.62 (p<0.001) for men. When including relevant biomarkers and conventional risk factors, little change was observed. When also controlling for moderate alcohol consumption and leisure-time physical activity, the OR in women was reduced to 1.24 (p=0.06). Little change was observed in men.

Conclusion

This study revealed an excess of APS, self-reported angina and a combination of these in Sami women and men relative to non-Sami women and men. Established risk factors explained little or none of the ethnic variation in APS. In women, however, less moderate alcohol consumption and leisure-time physical activity in Sami may explain the entire ethnic difference.

Cigarette smoking is associated with increased diastolic blood pressure among Chinese nonagenarians/centenarians

OBJECTIVE

Cigarette smoking has been confirmed as a factor influencing arterial blood pressure. In the present study, we studied whether cigarette smoking habits were still associated with arterial blood pressure among Chinese nonagenarians/centenarians.

METHODS

The present study analyzed data from a survey conducted on all residents aged 90 years or more in the DuJiangYan district (in total 2,311,709 inhabitants) in 2005.

RESULTS

The individuals included in the statistical analysis were 216 men and 445 women. Individuals who were heavy smokers (76.62 ± 13.28 mmHg) had higher diastolic blood pressure, compared with medium and light smokers (72.33 ± 12.98 and 70.28 ± 10.31 mmHg) (F = 3.551, p = 0.030). There was a higher prevalence of diastolic hypertension (21.62% vs 5.75% and 7.14%, χ(2 =) 6.302, p = 0.043). Furthermore, there was a higher risk for diastolic hypertension in heavy smokers (OR = 3.886, 95% CI 1.241-12.161) (adjusted) compared with medium (OR = 1.475, 95% CI 0.599-3.360) and light smokers (1.00 reference). There was, however, no significant difference in systolic blood pressure or prevalence of systolic hypertension among the different smoking groups.

CONCLUSIONS

In summary, we found that among Chinese nonagenarians/centenarians, heavy smoking (current or former) could increase diastolic blood pressure and prevalence of diastolic hypertension, but was not associated with changes in systolic blood pressure.

Effects of smoking on non-AIDS-related morbidity in HIV-infected patients

Tobacco smoking has many adverse health consequences. Patients with human immunodeficiency virus (HIV) infection smoke at very high rates, and many of the comorbidities associated with smoking in the general population are more prevalent in this population. It is likely that a combination of higher smoking rates along with an altered response to cigarette smoke throughout the body in persons with HIV infection leads to increased rates of the known conditions related to smoking. Several AIDS-defining conditions associated with smoking have been reviewed elsewhere. This review aims to summarize the data on non-AIDS-related health consequences of smoking in the HIV-infected population and explore evidence for the potential compounding effects on chronic systemic inflammation due to HIV infection and smoking.

A new set of risk equations for predicting long term risk of all-cause mortality using cardiovascular risk factors

OBJECTIVES

As population ages and treatment for cardiovascular disease improves the risk of all-cause mortality has become a more meaningful outcome. We develop all-cause mortality equations for predicting long term risk using cardiovascular risk factors.

METHODS

The 24-year risk of all-cause mortality was evaluated using Cox model for participants aged 40-81 years at the 10th or 11th examination of the Framingham original cohort and the first examination of the offspring cohort-all of whom were free of major chronic diseases.

RESULTS

The predictors of all-cause mortality were age, sex, systolic blood pressure, total cholesterol/HDL ratio and smoking status. Risk prediction improved significantly when intensity of smoking and time since quitting were included into smoking status. A reduced model based on non-laboratory risk factors also demonstrated good predictive performance.

CONCLUSIONS

All-cause mortality risk equations incorporating cardiovascular risk factors provide an improved tool to quantify risk and guide prevention of mortality. There are great potentials for prevention of the CVD epidemic and for increased longevity with health, through improved life-styles and consequent lower levels of blood pressure, cholesterol and smoking.

Age at quitting smoking as a predictor of risk of cardiovascular disease incidence independent of smoking status, time since quitting and pack-years

Background

Risk prediction for CVD events has been shown to vary according to current smoking status, pack-years smoked over a lifetime, time since quitting and age at quitting. The latter two are closely and inversely related. It is not known whether the age at which one quits smoking is an additional important predictor of CVD events. The aim of this study was to determine whether the risk of CVD events varied according to age at quitting after taking into account current smoking status, lifetime pack-years smoked and time since quitting.

Findings

We used the Cox proportional hazards model to evaluate the risk of developing a first CVD event for a cohort of participants in the Framingham Offspring Heart Study who attended the fourth examination between ages 30 and 74 years and were free of CVD. Those who quit before the median age of 37 years had a risk of CVD incidence similar to those who were never smokers. The incorporation of age at quitting in the smoking variable resulted in better prediction than the model which had a simple current smoker/non-smoker measure and the one that incorporated both time since quitting and pack-years. These models demonstrated good discrimination, calibration and global fit. The risk among those quitting more than 5 years prior to the baseline exam and those whose age at quitting was prior to 44 years was similar to the risk among never smokers. However, the risk among those quitting less than 5 years prior to the baseline exam and those who continued to smoke until 44 years of age (or beyond) was two and a half times higher than that of never smokers.

Conclusions

Age at quitting improves the prediction of risk of CVD incidence even after other smoking measures are taken into account. The clinical benefit of adding age at quitting to the model with other smoking measures may be greater than the associated costs. Thus, age at quitting should be considered in addition to smoking status, time since quitting and pack-years when counselling individuals about their cardiovascular risk.