Data collection
To obtain a significant sample of Albanian asthmatic population, a number of allergists/pathologists around the country were enrolled to contribute to the study by providing data about asthmatic subjects (18 years or older) based on their patient register and medical history. The study was retrospective, and medical records of 400 asthmatic subjects receiving montelukast (10 mg daily) and 400 asthmatic subjects not receiving montelukast were evaluated (from January 1st, 2012 to December 31st, 2014). Asthmatic subjects (International Classification of Diseases (ICD-10 v:2016) code 493) were diagnosed on the basis of GINA (Global Initiative for Asthma) criteria (https://ginasthma.org) on objective evidence of variable airflow obstruction. As the number of patients taking montelukast was the limiting factor of the study, we considered exposed all patients taking the drug for a period of at least three months, excluding all subjects with a previous history of MI or IS, as reported in their medical records (ICD: MI-I21 or IS-I63). These patients were randomly matched with patients not receiving montelukast as an anti-asthmatic drug primarily by gender and secondly by age. In order to identify a predisposition of the monitored patients to an increased CV risk for MI and IS, information was obtained on drug therapies for major chronic conditions such as hypertension, diabetes mellitus, dyslipidemia, cerebrovascular disease, anemia, arrhythmias, epilepsy, allergies, psychosis, ulcers, cancer, and depression. General information such as age, gender, patient education level, residence and income were also recorded, while systemic blood pressure, body mass index, smoking, obesity or cholesterol were not available for the majority of the patients and for this reason were not taken into account in our analysis. According to ICD, the two groups were finally classified for the presence or absence of MI or IS.