Discontinuation of and changes in drug therapy for hypertension among newly-treated patients: a population-based study in Italy.
OBJECTIVE
To assess rates and determinants of treatment discontinuation of or changes in initial antihypertensive drug therapy in a large cohort of patients from Lombardia (Italy).


METHODS
The cohort included 445356 patients aged 40 -80 years who received their first antihypertensive drug prescription (monotherapy) during 1999--2002. Discontinuation was defined by the absence of any antihypertensive prescription during a 90-day period following the end of the latest prescription. If during the same period a drug of a different class was added or replaced the initial prescription, treatment modification was regarded as combination or switching, respectively. Competing risks methodology was used to estimate and compare cause-specific cumulative incidence.


RESULTS
Cumulative incidences of discontinuation, combination and switching were respectively 33, 14 and 15% at 6 months, 41, 18 and 17% at 1 year, and 50, 25 and 19% at 5 years since initial treatment. Compared with patients starting treatment with angiotensin-converting enzyme inhibitors, the rate of discontinuation was less for patients on angiotensin receptor blockers with a hazard ratio of 0.92 (95% confidence interval =0.90-0.94), whereas increased discontinuation was observed for patients starting with other drugs, mainly beta-blockers with a hazard ratio of 1.64 (1.62-1.67); and diuretics with a hazard ratio of 1.83 (1.81-1.85).


CONCLUSIONS
In the general population of Lombardia, discontinuation of the initial single antihypertensive drug treatment is a common phenomenon, whereas switching to another monotherapy and to combination treatment occur at similarly much lower rates. Blockers of the renin-angiotensin system are associated with the lowest incidence of treatment discontinuation.
Corrao
Giovanni
G
Department of Statistics, Unit of Biostatistics and Epidemiology, University of Milano-Bicocca, Milan, Italy. giovanni.corrao@unimib.it
Zambon
Antonella
A
Parodi
Andrea
A
Poluzzi
Elisabetta
E
Baldi
Ileana
I
Merlino
Luca
L
Cesana
Giancarlo
G
Mancia
Giuseppe
G
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D047228:Angiotensin II Type 1 Receptor Blockers / Q000627:therapeutic use; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D015331:Cohort Studies; D016208:Databases, Factual; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000453:epidemiology*; D015994:Incidence; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012307:Risk Factors
D000319:Adrenergic beta-Antagonists; D047228:Angiotensin II Type 1 Receptor Blockers; D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents