The use of administrative data and natural language processing to estimate the incidence of statin-     related rhabdomyol...
Background: Statins and Rhabdomyolysis• Statins  – Reduce the risk of cardiovascular events and death  – Can cause a spect...
Background: Simvastatin• SEARCH:1 Secondary prevention trial  comparing simvastatin 80mg/day vs 20mg/day  – Rhabdomyolysis...
Background: Study of Rare ADRs• Spontaneous adverse event reports: FDA  AERS1  – Incomplete reporting of cases  – No infor...
Aims• Aim #1: Evaluate use of the new ICD-9 code for  rhabdomyolysis as a method of identifying cases  of statin-related r...
Methods• Setting: Group Health Cooperative, 2006-2010  – Electronic medical record introduced in 2005• Statin use estimate...
Methods• Rhabdomyolysis ICD-9 code (728.88)• Other methods:  – ICD-9 code for adverse event of a lipid agent  – CK level >...
Results: Case Identification                                           Validated                                Reviewed  ...
Results: Characteristics of Cases                                       Validated                                         ...
Results: Incidence Rates                      Validated Person-Years            IncidenceStatin                  Cases    ...
Results: Incidence Rate RatiosComparison                     Rhabdo ICD-9 Cases Validated CasesSimvastatin vs other statin...
Summary of Findings• Poor positive predictive value of rhabdomyolysis  ICD-9 code: 8%• NLP detected additional cases• Use ...
AcknowledgementsCardiovascular Health Research Unit, University of Washington        Bruce Psaty        Susan Heckbert    ...
THANK YOU
Potential ConfoundingSimvastatin dose Mean age Fibrate use20-39 mg/day       75        25%80+ mg/day          68        27%
Diffusion of rhabdo ICD-9 code         Cases: Cases:        Rhabdo Other   Simvastatin   Other    Simvastatin   OtherYear ...
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The Use of Administrative Data and Natural Language Processing to Estimate the Incidence of Statin Related Rhabdomyolysis FLOYD

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The Use of Administrative Data and Natural Language Processing to Estimate the Incidence of Statin Related Rhabdomyolysis FLOYD

  1. 1. The use of administrative data and natural language processing to estimate the incidence of statin- related rhabdomyolysis James Floyd, MD, MS HMORN Conference May 3, 2012
  2. 2. Background: Statins and Rhabdomyolysis• Statins – Reduce the risk of cardiovascular events and death – Can cause a spectrum of muscle injury• Rhabdomyolysis – Other causes: immobility, arterial ischemia, surgery – Rhabdomyolysis related to statin use occurs about once per 10,000 person-years of statin use
  3. 3. Background: Simvastatin• SEARCH:1 Secondary prevention trial comparing simvastatin 80mg/day vs 20mg/day – Rhabdomyolysis RR 26• FDA safety announcement: June 8, 2011 1. Lancet. 2010;376:1658.
  4. 4. Background: Study of Rare ADRs• Spontaneous adverse event reports: FDA AERS1 – Incomplete reporting of cases – No information about denominators• Administrative data in large health plans2 – Difficult to identify “statin-related” cases – Among statin users in 11 health plans, only 24/194 (12%) of potential cases were validated• Rhabdomyolysis ICD-9 code introduced in 2006 1. Staffa JA. NEJM. 2002;346:539. 2. Graham DJ. JAMA. 2004;292:2585.
  5. 5. Aims• Aim #1: Evaluate use of the new ICD-9 code for rhabdomyolysis as a method of identifying cases of statin-related rhabdomyolysis• Aim #2: Determine whether the markedly increased risk of rhabdomyolysis associated with high-dose simvastatin use can be detected using these methods
  6. 6. Methods• Setting: Group Health Cooperative, 2006-2010 – Electronic medical record introduced in 2005• Statin use estimated from computerized prescription data• Statin-related rhabdomyolysis: Muscle symptoms with peak creatine kinase (CK) level ≥ 10x ULN, no other cause
  7. 7. Methods• Rhabdomyolysis ICD-9 code (728.88)• Other methods: – ICD-9 code for adverse event of a lipid agent – CK level > 5x ULN in GHC laboratory database – Natural language processing (NLP)• Incidence rates estimated from cases divided by person-years of statin use – One set of cases identified only by rhabdo ICD-9 code – Second set of cases validated by EMR review
  8. 8. Results: Case Identification Validated Reviewed CasesCase identification method N N %Rhabdomyolysis ICD-9 292 22 8%Other criteria AE of lipid agent ICD-9 30 1 3% CK > 1000 IU/L 39 1 3% Natural language processing 438 5 1%Total, all methods 799 29
  9. 9. Results: Characteristics of Cases Validated Cases N=29Age, median (range) 73 (53-87)Female 18 (62%)Hospitalized 26 (90%)Renal failure 8 (29%)Hemodialysis 2 (7%)Death 0 (0%)Creatine kinase, median (range) 7,450 (1,477-150,510)
  10. 10. Results: Incidence Rates Validated Person-Years IncidenceStatin Cases Statin Use Rate* 95% CISimvastatin 23 170,605 14 9-20 <20 mg/day 0 21,832 0 0-17 20-39 mg/day 4 75,082 5 2-14 40-79 mg/day 8 56,703 14 6-28 ≥80 mg/day 11 18,876 65 32-117Other statins** 6 116,154 5 2-11 *Cases per 100,000 person-years statin use **Non-simvastatin use primarily lovastatin (69%) and atorvastatin (24%)
  11. 11. Results: Incidence Rate RatiosComparison Rhabdo ICD-9 Cases Validated CasesSimvastatin vs other statins 1.0 2.6 (95% CI) (0.8 - 1.3) (1.0 - 7.8)Simvastatin 80mg vs 20mg 1.8 12.2 (95% CI) (1.1 - 2.9) (3.6 - 52)
  12. 12. Summary of Findings• Poor positive predictive value of rhabdomyolysis ICD-9 code: 8%• NLP detected additional cases• Use of administrative data without medical record review may fail to detect important harms• Confirmed in a community setting the increased risk with high dose simvastatin in SEARCH trial
  13. 13. AcknowledgementsCardiovascular Health Research Unit, University of Washington Bruce Psaty Susan Heckbert Noel WeissGroup Health Research Institute, Group Health Cooperative David Carrell Eric LarsonNHLBI T32 Training Grant PI David SiscovickNHLBI grants HL078888 and HL085251 PI Bruce Psaty
  14. 14. THANK YOU
  15. 15. Potential ConfoundingSimvastatin dose Mean age Fibrate use20-39 mg/day 75 25%80+ mg/day 68 27%
  16. 16. Diffusion of rhabdo ICD-9 code Cases: Cases: Rhabdo Other Simvastatin Other Simvastatin OtherYear ICD9 methods P-Y P-Y Cases Cases2006 2 0 13,750 36,758 0 22007 2 2 22,034 31,082 2 22008 4 2 41,709 15,827 5 12009 8 1 45,171 15,755 8 12010 6 2 47,940 16,732 8 0

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