Objectives: To measure persistence with antihypertensive drug therapy in patients initiating treatment with mono or combination therapy.
Methods: Data analysis was based on two cohorts of patients, that is, a cohort derived from the registration of drug prescriptions in all residents of the Lombardy region receiving Public Health Service and a cohort of patients followed by general practitioners throughout the Italian territory. Data were limited to patients aged 40–80 years who received their first antihypertensive drug prescription (n = 433680 and 41199, respectively) in whom persistency of treatment was examined over 9 months. A proportional hazards model was fitted to estimate the association between the pattern of initial antihypertensive drug therapy and risk of treatment discontinuation. Data were adjusted for available potential confounders.
Results: Taking patients starting with diuretic monotherapy as reference, the adjusted risk of treatment discontinuation was progressively lower in patients starting with monotherapy other than a diuretic, a two-drug combination, including a diuretic and a two-drug combination without a diuretic. No significant difference in the risk of discontinuation was seen between extemporaneous and fixed dose combinations, including a diuretic, that is, the only combination reimbursable by Public Health Service and, thus, available in the database. Data were similar for the two cohorts.
Conclusion: Initiating treatment with a combination of two drugs is associated with a reduced risk of treatment discontinuation.
aDepartment of Statistics, Unit of Biostatistics and Epidemiology, University of Milano-Bicocca, Italy
bBKL Consulting s.r.l., Milan, Italy
cItalian College of General Practitioners, Italy
dHealth Search, Florence, Italy
eOperative Unit of Territorial Health Services, Region Lombardia, Italy
fDepartment of Clinical and Preventive Medicine, University of Milano-Bicocca, Milan, Italy
Received 11 January, 2010
Revised 23 February, 2010
Accepted 17 March, 2010
Correspondence to Professor Giovanni Corrao, Dipartimento di Statistica, Unità di Biostatistica ed Epidemiologia, Università degli Studi di Milano-Bicocca, via Bicocca degli Arcimboldi, 8, Edificio U7, 20126 Milan, Italy Tel: +39 02 64485854; fax: +39 02 64485899; e-mail: firstname.lastname@example.org