ROLE OF INTERACTIONS BETWEEN PSYCHOLOGICAL AND CLINICAL FACTORS IN DETERMINING 6-MONTH MORTALITY AMONG PATIENTS WITH ACUTE MYOCARDIAL-INFARCTION - APPLICATION OF RECURSIVE PARTITIONING TECHNIQUES TO THE GISSI-2 DATABASE

Background Clinical and epidemiological studies support the hypothesis that ischaemic cardiovascular diseases are consistently associated wi th psychological, social and behavioural factors. Nevertheless, the jo int effect of clinical characteristics and psychological variables in determining the prognosis of acute myocardial infarction survivors has been seldom investigated. Methods and Results In the framework of the GISSI-2 trial, the impact of psychological factors on 6-month mortali ty and their interaction with clinical features was included as an ad hoc research project. Overall, 2449 patients were evaluated, 63 of who m died during the study period. All patients undertook a self-administ ered questionnaire (Cognitive Behavioural Assessment Hospital Form), i nvestigating 16 psychological dimensions relative to three areas (stat e variables, vital exhaustion, trait variables). The impact of psychol ogical variables on prognosis and their interaction with clinical vari ables were investigated by using a tree-growing technique (RECursive P artitioning and AMalgamation - RECPAM) applied to survival analysis. T his statistical method allowed the identification of three separate cl asses, characterized by different prognoses: Class I (presence of vita l exhaustion), Class II (concomitance of no vital exhaustion, depressi on and low levels of anxiety) and Class III (all other patients). Afte r adjusting for the clinical variables, Class I was associated with an intermediate prognosis (hazard ratio [HR]=2.2; 95% confidence interva ls [CI] 1.2-4.0) and Class II to the worst (HR=3.2; 95% CI=1.6-6.2), a s compared to Class III. High levels of neuroticism and extroversion w ere associated with a better prognosis. When clinical and psychologica l variables were simultaneously investigated by RECPAM, Type A behavio ur was shown to be an important risk predictor among patients with bet ter clinical conditions, i.e. those eligible for exercise test (HR=2.6 , 95% CI=1.2-5.5). Finally, a striking difference in the impact of the most predictive clinical variables (exercise test ineligibility, late and early ventricular failure) was found among patients with and with out vital exhaustion. Conclusions This study shows that acute myocardi al infarction survivors are heterogeneous with respect to 6-month mort ality according to their psychological profile. More important, the im pact of these variables appears comparable to that of very well known clinical risk predictors. The availability of a large study population , together with the use of innovative statistical techniques, allowed us to identify subgroups of patients for whom the joint action of clin ical and psychological characteristics has been clearly documented. Th is suggests the need for incorporating psychological evaluation in the care of acute myocardial infarction patients.