Summary
Background
Cardiovascular disease (CVD) is the primary cause of premature death in Western countries.
Aim
To assess the effect of patient ignorance of CVD risk modifiers on mortality.
Methods
We studied 4930 men and women in primary prevention, who consulted at the Department of Preventive Cardiology of a university hospital in France from 1995 to 2011. Questionnaires on socioeconomic level, medical history, cardiovascular risk factors, knowledge of CVD, drug intake, lifestyle and dietary recommendations, and adherence to treatments were administered by trained medical staff. Vital status (cause and date of death, in patients who died) was obtained through the French National Database. Multivariable predictive relationships with total mortality were evaluated using the Cox proportional hazards model.
Results
Mean follow-up was 8.6 years; 123 deaths, including 31 cardiovascular deaths, were recorded. Overall, 1305 patients (26%) were ignorant of CVD preventive measures; their mean age (53 years) was similar to that of the non-ignorant population, but most were men with a low educational level, a higher body mass index and significantly more cardiovascular risk factors (diabetes, hypertension). The ignorant group’s lifestyle did not conform to cardiovascular guidelines, with less physical activity and more frequent inappropriate diet and smoking. All-cause and cardiovascular mortalities were higher among these patients. In the multivariable analysis, after adjusting for age, sex, smoking status, diabetes, hypertension, body mass index and educational status, ignorance of CVD preventive measures remained significantly associated with all-cause mortality (hazard ratio 1.93, 95% confidence interval 1.31–2.83; P < 0.01).
Conclusion
Ignorance of cardiovascular risk modifiers was significantly associated with all-cause mortality in a general French population.
Résumé
Contexte
Les maladies cardiovasculaires représentent la première cause de mortalité prématurée dans les pays développés.
Objectif
Nous avons évalué l’effet de la méconnaissance du risque cardiovasculaire sur la mortalité.
Méthodes
Nous avons étudié 4930 femmes et hommes en prévention primaire qui ont consulté de 1995 à 2011 dans le service de cardiologie préventive d’un hôpital universitaire français. Des questionnaires portant sur le niveau socio-économique, la connaissance des maladies cardiovasculaires, l’hygiène de vie et les recommandations diététiques, les antécédents médicaux, la prise de médicaments, l’observance et les facteurs de risque cardiovasculaire ont été administrés par un médecin entraîné. Le statut vital (causes et date du décès) a été obtenu à partir de la base nationale des décès. Une analyse multivariée évaluant la mortalité totale a été réalisée en utilisant un modèle de Cox.
Résultats
Le suivi moyen des 4930 patients a été de 8,6 ans et 123 décès (incluant 31 décès cardiovasculaires) ont été enregistrés. Un total de 1305 sujets (26 %) ne connaissent aucune mesure de prévention cardiovasculaire. Leur âge était similaire (53 ans) au reste de la population mais ces sujets étaient plus souvent des hommes avec un niveau d’éducation relativement bas, un indice de masse corporelle plus élevé et significativement plus de facteurs de risque cardiovasculaire (diabète, hypertension). Leur mode de vie n’était pas conforme aux recommandations cardiovasculaires, avec moins d’activité physique et plus souvent une diététique inappropriée et plus souvent tabagiques. Les mortalités totale et cardiovasculaire étaient plus élevées parmi les sujets ne connaissant pas les mesures de prévention cardiovasculaire. Lors de l’analyse multivariée, après ajustement pour l’âge, le sexe, le tabagisme, le diabète, l’hypertension artérielle, l’indice de masse corporelle et le niveau d’éducation, l’absence de connaissance des mesures de prévention cardiovasculaire est associée significativement à la mortalité totale ( hazard ratio 1,93, IC95 % 1,31–2,83 ; p < 0,01).
Conclusion
La méconnaissance des mesures qui modifient le risque cardiovasculaire est significativement associée à la mortalité totale en population française.
Background
Progress in pharmacological and interventional treatments and in preventive medicine has led to a decrease in the consequences of cardiovascular disease (CVD) in terms of mortality and morbidity . Prevention accounts for a major part of this progress: the reduction in major cardiovascular risk factors, such as tobacco use, arterial hypertension and dyslipidaemia, is estimated to account for more than 50% of the decrease in cardiovascular deaths . There is, however, still plenty of room for improvement, as a large proportion of patients do not follow lifestyle advice and dietary prescriptions, and do not achieve their therapeutic objectives . The combination of underuse of therapeutic education and unsatisfactory adherence to recommended CVD prevention measures continues to take its toll on mortality.
The effect on mortality of adherence to lifestyle and dietary recommendations and treatments has been widely studied . On the other hand, the role of knowledge of preventive measures for CVD has received little attention . Yet, understanding the disease is of primary importance in preventive medicine, notably to ensure better adherence; this is one of the main aims of therapeutic education . In cardiology, knowledge of the disease seems even more important because, beyond preventive measures, recognising the warning signs of myocardial infarction, for example, and knowing how to manage them can be life saving.
Our aim was to study knowledge of primary preventive measures for CVD in the general population, and its relationship with all-cause and cardiovascular mortality.
Methods
Patient population
We conducted a prospective cohort study that included 6956 apparently healthy asymptomatic men and women. Participants were included between November 1995 and December 2011 in the Department of Preventive Cardiology of our teaching institution (Toulouse University Hospital, Toulouse, France). The patients were either self referred or referred by their primary care physician or cardiologist for cardiovascular risk assessment, management of cardiovascular risk factors or routine ambulatory screening for CVD . Patients with a history of coronary heart disease (International Classification of Disease, 9th revision, codes 410.0 to 414.9), stroke (codes 433.0 to 438.9 except 437.3 to 437.7), atherosclerosis (codes 440.0 to 440.9) or aneurysms (codes 441.0 to 442.9) were excluded. Vital status on 31 December 2011 was obtained for each patient through the national database that records all deaths occurring in the French population each year (Répertoire national d’identification des personnes physiques [RNIPP]) . Authorization to use these data was obtained in accordance with French law (Commission nationale de l’informatique et des libertés [CNIL]).
Questionnaires and measurement of clinical variables
At baseline, extensive questionnaires were completed by trained medical staff during an interview with the patient. The physician carrying out the interview ensured good understanding of the questions. Information on exposures was collected at baseline only. Data concerning socioeconomic level, medical history, cardiovascular risk factors, lifestyle habits and drug intake were recorded. Patients were asked to bring their latest drug prescription to the inclusion visit. In particular, ignorance of CVD was defined by the question: “In your opinion, are there any precautions that can be taken to avoid a heart disease such as myocardial infarction?”. The answer was quoted “No” if the patient was unable to give the name of a classical risk factor or to propose any lifestyle measures. Educational level was defined by the highest diploma obtained by the patient: a diploma lower than the high school diploma (education until age 18 years) was considered as a low educational level. All drugs taken during the 2 weeks preceding the visit were recorded. Family history of premature CVD (before the age of 55 years in the father or 65 years in the mother) was recorded. People who currently smoked or who had stopped for less than 3 years were considered as current smokers. Height, weight and arterial blood pressure (mean of two measurements performed with a standard sphygmomanometer in a seated position after at least 5 minutes of rest) were measured by the medical staff according to standardized protocols. Body mass index was calculated as weight divided by height squared (kg/m 2 ). Diabetes was defined as diabetes treated with oral antidiabetic agents or insulin; dyslipidaemia was defined as dyslipidaemia treated with statins; and hypertension was defined as hypertension treated with antihypertensive drugs. For those patients requiring dietary measures (for hypertension, diabetes or dyslipidaemia), adherence to the diet was assessed by the question “Do you follow a diet for your hypertension/diabetes/cholesterol?”.
Laboratory methods
Blood samples were taken after at least 10 hours of overnight fasting. Serum total cholesterol and triglycerides were measured by enzymatic assays (Boehringer, Mannheim, Germany). High-density lipoprotein (HDL) cholesterol was measured after sodium phosphotungstate-magnesium chloride precipitation of apolipoprotein B-containing lipoproteins. Low-density lipoprotein (LDL) cholesterol was determined by the Friedewald formula when triglycerides were below 4.6 mmol/L (400 mg/dL) . Glucose concentrations were measured using a conventional enzymatic method based on hexokinase-glucose-6-phosphate dehydrogenase.
Statistical analysis
Statistical analysis was performed on STATA statistical software, version 11.2 (STATA Corporation, College Station, TX, USA).
First, we described the baseline characteristics of the patients and compared these characteristics by outcome occurrence, comparing patients who remained alive (on 31 December 2011) with patients who died during follow-up. Qualitative variables were compared between groups using the χ 2 test or Fisher’s exact test when necessary. Student’s t test was used to compare the distribution of quantitative data; the Mann–Whitney U test was used when the distribution departed from normality or when homoscedasticity was rejected. Following the same method, we then compared baseline characteristics of patients according to their “ignorant” versus “non-ignorant” status.
Survival was also analysed, with events being cases of death. Hazard ratios (HRs) for mortality and 95% confidence intervals (CIs) were assessed using a Cox model. The independent variables initially introduced in the survival model were all variables associated with mortality in the univariate analysis with a P -value < 0.10. A backward analysis was then applied until only variables significantly and independently associated with mortality ( P < 0.05) remained. The proportional-hazard assumption was tested for each covariate by “log-log” plot method curves (–ln[–ln(survival)]), for each category of nominal covariate, versus ln(analysis time). None of the assumptions could be rejected. The same survival analysis was conducted with the cases of cardiovascular death as events.
To evaluate the causal effect of ignorance on mortality, and to reduce bias caused by confounding variables, a propensity score matching analysis was conducted . We first estimated a propensity score including all the baseline characteristics of the patients. The balancing property of the propensity score was tested. All variables leading to an unbalanced property of the propensity score were excluded, and a new propensity score was calculated until the balancing property was satisfied. Ignorant patients were matched one-to-one with non-ignorant patients using the nearest neighbour method, defining a matched cohort (ignorant versus non-ignorant). We conducted the same survival analysis, adding the propensity score as a new covariate in the global study population and in the matched cohort . These analyses were successively conducted with all-cause mortality and cardiovascular mortality.
Results
General data
A total of 6956 patients visited the Department of Preventive Cardiology from November 1995 to December 2011. After excluding minors and patients with CVD at inclusion, as well as patients who returned to the same department on several occasions, we reached a total of 4930 patients who were followed up until 31 December 2011 ( Fig. 1 ).
The mean age of the 4930 patients was 53 years and 59% were men ( Table 1 ). During the mean follow-up of 8.6 years, 123 deaths (including 31 cardiovascular deaths) were recorded. The other main cause of death was cancer (49%). Other causes (trauma, suicide, infectious disease, chronic obstructive pulmonary disease) represented 26% of all deaths. The patients who died were older (55 ± 11 vs 53 ± 11 years; P < 0.01) and most were men (86% vs 59%; P < 0.01); a higher percentage had a low educational level (78% vs 62%; P < 0.01) and there was a higher proportion of diabetic patients (15% vs 5%; P < 0.01). The patients who died also had less favourable blood pressure and lipid profiles, with a mean systolic blood pressure of 146 ± 20 mmHg (vs 136 ± 18 mmHg; P < 0.01) and an LDL cholesterol concentration of 4.37 ± 1.21 mmol/L (vs 3.99 ± 1.18 mmol/L; P < 0.01).
| All ( n = 4930) | Alive ( n = 4807) | Deceased ( n = 123) | P | |
|---|---|---|---|---|
| Age (years) | 53 ± 11 | 53 ± 11 | 55 ± 11 | < 0.01 |
| Men | 2927 (59) | 2821 (59) | 106 (86) | < 0.01 |
| Educational level < high school completion | 3095 (63) | 2999 (62) | 96 (78) | < 0.01 |
| Family history of premature CVD | 723 (15) | 708 (15) | 15 (12) | 0.43 |
| Tobacco use | 1248 (25) | 1198 (25) | 50 (41) | < 0.01 |
| Diabetes | 255 (5) | 237 (5) | 18 (15) | < 0.01 |
| Hypertension | 981 (20) | 952 (20) | 29 (24) | 0.30 |
| Dyslipidaemia | 1323 (27) | 1298 (27) | 25 (20) | 0.10 |
| Body mass index (kg/m 2 ) | 26 ± 5 | 26 ± 5 | 27 ± 5 | 0.04 |
| Systolic blood pressure (mmHg) | 136 ± 18 | 136 ± 18 | 146 ± 20 | < 0.01 |
| Diastolic blood pressure (mmHg) | 82 ± 9 | 82 ± 9 | 86 ± 10 | < 0.01 |
| Pulse pressure (mmHg) | 54 ± 13 | 54 ± 13 | 60 ± 15 | < 0.01 |
| Total cholesterol (mmol/L) | 6.17 ± 1.29 | 6.15 ± 1.30 | 6.46 ± 1.35 | 0.01 |
| LDL cholesterol (mmol/L) | 4.00 ± 1.19 | 3.99 ± 1.18 | 4.37 ± 1.21 | < 0.01 |
| HDL cholesterol (mmol/L) | 1.41 ± 0.42 | 1.41 ± 0.42 | 1.29 ± 0.38 | < 0.01 |
| Triglycerides (mmol/L) | 1.75 ± 1.72 | 1.75 ± 1.73 | 1.79 ± 1.22 | 0.79 |
| Alcohol | < 0.023 | |||
| No alcohol consumption | 1370 (28) | 1340 (28) | 30 (24) | |
| Consumption < 20 g/day for men, < 10 g/day for women | 2140 (43) | 2087 (44) | 44 (36) | |
| Consumption > 20 g/day for men, > 10 g/day for women | 1420 (29) | 1371 (29) | 49 (40) | |
| Physical activity | 0.59 | |||
| No regular physical activity | 1256 (25) | 1220 (25) | 36 (29) | |
| Light physical activity every week | 2641 (54) | 2577 (54) | 64 (52) | |
| Intense physical activity for ≥ 20 minutes, one to two times/week | 837 (17) | 820 (17) | 17 (14) | |
| Intense physical activity for ≥ 20 minutes, > three times/week | 186 (4) | 180 (4) | 6 (5) | |
| Diet | 0.16 | |||
| Diet not followed | 761 (35) | 736 (35) | 25 (44) | |
| Diet followed | 1404 (64) | 1372 (65) | 42 (56) | |
| Ignorance of CVD preventive measures | 1305 (26) | 1256 (26) | 49 (40) | < 0.01 |
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