title: Frequency and predictors of tablet splitting in statin prescriptions: a population-based analysis.
abstract: BACKGROUND
  The price per milligram for most statin medications decreases at higher strengths, which provides an economic incentive to split tablets. We sought to determine the frequency with which statin tablets are split, and to evaluate factors associated with this practice.
  
  
  METHODS
  We obtained prescription claims data for statins from the BC Ministry of Health for the period Jan. 1, 1996, to Dec. 31, 2006. We estimated the number of tablets per day, based on the ratio of the number of tablets to days-supply in each prescription, to estimate the frequency with which splitting occurred with each statin. We used multivariable logistic regression to assess patient and physician characteristics and the level of public drug plan coverage associated with tablet splitting. To estimate related cost savings, we used information on drug costs and quantities of dispensed statins reported by pharmacies.
  
  
  RESULTS
  During the 11-year study period, we estimated that tablet splitting occurred in 2.6% of 7.2 million statin prescriptions. There was an increasing trend in the practice over time, to 4.5% of prescriptions in 2006. Lovastatin was the only scored tablet and was the most likely to be split, followed by rosuvastatin and atorvastatin. Fifty percent of the prescriptions in which tablet splitting occurred were prescribed by only 7.9% of the routine statin prescribers (i.e., > 10 statin prescriptions over the study period). Specialists were less likely than general practitioners to prescribe statins that were subsequently split (odds ratio [OR] 0.43, 95% confidence interval [CI] 0.40-0.46). Statin prescriptions that were fully covered by the public drug plan were half as likely as those with no such coverage to involve tablet splitting (OR 0.48, 95% CI 0.44-0.92). Having no public drug coverage, having a low annual household income and being female were patient factors found to be positively associated with tablet splitting. In 2006, the cost savings associated with tablet splitting was $2.3 million.
  
  
  CONCLUSIONS
  The frequency of tablet splitting in statin prescriptions in British Columbia was low but increased over time. It varied between patients, physicians and different levels of insurance coverage. In the final study year, 94.5% of the statin prescriptions were dispensed at strengths for which a tablet of twice the strength was available and could have been split, which suggests a potentially enormous cost savings.
authors: Colin R
authors: CR
authors: Dormuth
authors: Sebastian
authors: S
authors: Schneeweiss
authors: Alan M
authors: AM
authors: Brookhart
authors: Greg
authors: G
authors: Carney
authors: Ken
authors: K
authors: Bassett
authors: Stephen
authors: S
authors: Adams
authors: James M
authors: JM
authors: Wright
references: Am J Epidemiol. 1999 Mar 15;149(6):541-9
references: 10084243
references: Am J Health Syst Pharm. 1999 Dec 15;56(24):2542-5
references: 10613374
references: Clin Ther. 2006 Jun;28(6):964-78; discussion 962-3
references: 16860179
references: Eur J Clin Pharmacol. 2006 Dec;62(12):1065-73
references: 17024485
references: CNS Drugs. 2002;16(5):353-8
references: 11994024
references: Eur J Pharm Sci. 2004 Feb;21(2-3):305-8
references: 14757502
references: J Manag Care Pharm. 2002 Nov-Dec;8(6):453-8
references: 14613379
references: Med Care. 1994 Jan;32(1):81-90
references: 8277803
references: J Manag Care Pharm. 2006 Jul-Aug;12(6):449-56
references: 16925452
references: Health Care Financ Rev. 1995 Summer;16(4):189-99
references: 10151888
references: Clin Ther. 2003 Jan;25(1):273-84
references: 12637126
references: Ann Pharmacother. 2002 Feb;36(2):205-9
references: 11847935
references: Inquiry. 1993 Summer;30(2):199-207
references: 8314608
references: Am J Public Health. 1992 Feb;82(2):243-8
references: 1739155
references: Pharmacoeconomics. 2005;23(10):1021-30
references: 16235975
references: Am J Cardiol. 2005 Jun 15;95(12):1481-3
references: 15950578
references: Am J Manag Care. 2002 Aug;8(8):706-12
references: 12212758