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What Do You Do When There Is No Evidence?

What Do You Do When There Is No Evidence?. Dr. Jack McCarthy Bi-Valley Medical Clinic Sacramento, CA jmccarthy@bivalley.com. What is a Long QT?. ICH-E14 – International Conference on Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICHTRPHU)

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What Do You Do When There Is No Evidence?

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  1. What Do You Do When ThereIs No Evidence? Dr. Jack McCarthy Bi-Valley Medical ClinicSacramento, CA jmccarthy@bivalley.com

  2. What is a Long QT? ICH-E14 – International Conference on Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICHTRPHU) Provides guidance for clinical evaluation of QT for new medications ICH-14 states there is no consensus regarding the upper limit of value of the QT interval and what constitutes significant changes from baseline. Over 500ms has some kind of risk??

  3. Can Anyone Identify a Long QT? Inaccurate EKG interpretation of long QT. The majority of physicians cannot recognize a long QT when they see one. Viskin et all, Heart Rhythm, June 2005. 902 physicians (25 QT experts, 106 arrhythmia experts, 329 cardiologists, 442 non-cardiologists) tested. Correct classification of all QT intervals was achieved by 96% of QT experts, 62% of arrhythmia experts, and < 25% of cardiologists and non-cardiologists. Problem: Inability to define where the T wave ends; most common errors were false positives and false negatives. Conclusion: only arrhythmia experts with special interest in the LQTS can be reliably trusted with QT measurements. 2 other studies support the same conclusion.

  4. The Uncertainty Principle: QTc Is there any certainty to this whole literature? Cardiologists can’t tell where the T wave ends, and machines confuse the T and U waves. What does it mean that so many ‘experts’ get it wrong? Is the totally accurate QT measurement the Search for the Holy Grail (Monty Python version?)

  5. What Do Counselors Need to Know and Do? Any history of cardiac disease Any family history of death at an early age for no apparent reason. All medications the patient is taking, updated frequently, including illicit drugs like cocaine. Any episode of fainting or loss of consciousness Coordinate with medical staff

  6. CSAT QT ‘Guideline’: Evidence-Based? • No QT expert on panel. No economist. • Selection bias, another group would have different recommendations. • Minority opinion was expunged from the publication. • Publication by-passed scientific review. • EKG machine inaccuracy not discussed. • The literature was merely reported, not scientifically critiqued.

  7. CSAT QT ‘Guideline’: Evidence-Based? (con’t) 40 years of evidence of methadone safety ignored. NIDA START study 1000 patients, no cardiac signals. There is no evidence for the recommendation of serial EKGs or dose reductions with QT>500ms, except “the Panel is convinced that it will save lives”, recommendations without a single supporting study. What NEJM editorial calls expert dogma.

  8. CSAT QT ‘Guideline’: Evidence-Based? Conclusions. CSAT draft recommendation for universal serial EKGs is level C, class II: expert opinion, and uncertainties about right decisions.

  9. The Fainting Danes? Fanoe et al: Syncope and QT prolongation in patients treated with methadone for heroin dependence in the city of Copenhagen, Heart 2007;93:1051-55. 393 methadone patients showing QT prolongation (>440ms) in 32%. 21% report ‘syncope’ in the past year? ‘Syncope’ was not studied, beyond one question: did you ever faint when you were not injecting or snorting drugs? What about alcohol, pills, medications? No information on medical conditions or medications (mean age 40), no EKG information beyond QTc. Significant illicit drug abuse was not evaluated for its relationship to the ‘syncope’. Alcohol and nicotine were not mentioned at all in the report. The population was so poorly characterized that all you can say was they were aging, used a lot of drugs, including drugs, like cocaine, that prolong QT. This very poor study was cited by Krantz et al without any critique, what Shaneyfelt reported 10 years ago as a major problem with CPGs: an inability to evaluate the scientific evidence.

  10. Methadone’s Cardiac Safety: Norwegian Mortality Data Prevalence and clinical relevance of QTc interval prolongation during methadone and buprenorphine treatment: a mortality assessment study. Anchersen et al, Addiction, 2009. “The clinical relevance and mortality attributable to methadone’s QT effect is unknown.” Population: 2382 patients with 6450 total years in OMT 173 EKGs: 4.6% (N=8) of methadone had QTc > 500. 29% had a QT >450 Mortality in which TdP could not be excluded was 0.06/100 patient years. Only one death in 3850 inductions occurred in the first month of treatment. Conclusion: Maximum mortality attributable to TdP was very low. We do not believe that implementation of routine EKGs prior to OMT initiation would have had any significant impact on mortality. This study suggests that the CSAT draft might be class III: evidence that EKG screening recommendation may be harmful by imposing barriers to care and proper dosing that is of greater risk than the risk of TdP.

  11. The Art of Medicine “In Hippocrates Shadow”: What doctors don’t know and won’t tell you. David Newman, M.D. Questions the reality of evidence-based medicine.

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