title: Intended and unintended consequences of the gabapentin off-label marketing lawsuit among patients with bipolar disorder.
abstract: OBJECTIVE
  The number of lawsuits accusing pharmaceutical companies of off-label marketing has risen in recent years. The impact of such lawsuits on drug prescribing and spending has not been examined. We evaluated a nationwide sample to determine whether the $430 million gabapentin off-label marketing lawsuit and accompanying media coverage affected gabapentin market share, substitution of other scientifically substantiated and unsubstantiated anticonvulsants, and anticonvulsant spending of Medicare/Medicaid patients diagnosed with bipolar disorder.
  
  
  METHODS
  Using a national 5% sample of Medicare recipients linked to Medicaid claims, we used an interrupted times series design to evaluate the impact of the lawsuit on monthly market share, utilization, and spending from January 1, 2001, to December 31, 2005.
  
  
  RESULTS
  The start of the lawsuit was associated with a 28% relative reduction in gabapentin market share (from ∼ 21% to ∼ 15%) and a reduction in the rate of prescribing from 108 prescriptions per 1,000 patients per month before the start of the lawsuit to 90 by the end of follow-up (P < .001). We also observed increases in market share for 3 other anticonvulsants. Total anticonvulsant use and spending per 1,000 patients increased by 13% and 74%, respectively, after the intervention. The increase in anticonvulsant spending was equivalent to $7,554 per 1,000 patients per year higher than expected compared with the baseline trend (P = .01).
  
  
  CONCLUSIONS
  We conclude that the lawsuit resulted in a reduction in gabapentin market share, increased market share for other anticonvulsants, and substantially increased total anticonvulsant spending to approximately half of the settlement amount, not counting substitutions of newer drugs for other illnesses affected by the lawsuit. These findings support the need for further study of the effects of current lawsuits regarding off-label drug marketing.
authors.affiliation: Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care, 133 Brookline Ave, 6th Floor, Boston, MA 02215, USA. mchace@fas.harvard.edu
authors.forename: Meredith J
authors.initials: MJ
authors.lastname: Chace
authors.forename: Fang
authors.initials: F
authors.lastname: Zhang
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Fullerton
authors.forename: Haiden A
authors.initials: HA
authors.lastname: Huskamp
authors.forename: Daniel
authors.initials: D
authors.lastname: Gilden
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Soumerai
mesh_terms: D000588:Amines / Q000009:adverse effects / Q000191:economics / Q000627:therapeutic use*; D000927:Anticonvulsants / Q000009:adverse effects / Q000191:economics / Q000627:therapeutic use*; D001714:Bipolar Disorder / Q000188:drug therapy* / Q000523:psychology; D035881:Compensation and Redress / Q000331:legislation & jurisprudence; D003509:Cyclohexanecarboxylic Acids / Q000009:adverse effects / Q000191:economics / Q000627:therapeutic use*; D017277:Drug Approval / Q000191:economics / Q000331:legislation & jurisprudence; D016527:Drug Costs / Q000331:legislation & jurisprudence; D004345:Drug Industry / Q000191:economics / Q000331:legislation & jurisprudence*; D004346:Drug Information Services / Q000191:economics; D057915:Drug Substitution / Q000191:economics / Q000706:statistics & numerical data; D004363:Drug Utilization / Q000191:economics / Q000331:legislation & jurisprudence / Q000706:statistics & numerical data; D000077206:Gabapentin; D006801:Humans; D007356:Insurance, Pharmaceutical Services / Q000191:economics / Q000331:legislation & jurisprudence / Q000706:statistics & numerical data; D040541:Marketing / Q000191:economics / Q000331:legislation & jurisprudence*; D008402:Mass Media / Q000706:statistics & numerical data; D008484:Medicaid / Q000191:economics / Q000331:legislation & jurisprudence / Q000706:statistics & numerical data; D006278:Medicare / Q000191:economics / Q000331:legislation & jurisprudence / Q000706:statistics & numerical data; D056687:Off-Label Use / Q000191:economics / Q000331:legislation & jurisprudence*; D010818:Practice Patterns, Physicians' / Q000191:economics / Q000331:legislation & jurisprudence* / Q000706:statistics & numerical data; D016896:Treatment Outcome; D014481:United States; D005680:gamma-Aminobutyric Acid / Q000009:adverse effects / Q000191:economics / Q000627:therapeutic use*
chemical_list: D000588:Amines; D000927:Anticonvulsants; D003509:Cyclohexanecarboxylic Acids; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin