Notes on Evidence-Based Medicine and Data Transparency

What Epidemiology Is

  • Epidemiology is the science of how we know in the real world whether something is good for you or bad for you.
  • It helps explain why sensational headlines (e.g., about coffee, Wi‑Fi, or olive oil) can be inconsistent or misleading.
  • The aim is to unpick the evidence behind claims; this is socially useful and a powerful explanatory tool.

Core Idea: Evidence-Based Medicine (EBM)

  • EBM = critical appraisal of evidence to determine what really helps or harms people.
  • It relies on data, not authority or prestige.
  • Academic critique (e.g., Q&A in journals) is normal and valuable.

Weakest Form of Evidence: Authority

  • Authority alone is unreliable in science; reasons matter more than titles.
  • Example: Gillian McKeith (TV diet guru) with an unaccredited PhD and dubious credentials; illustrates why credentials aren’t enough.

From Headlines to Proper Science

  • Red wine and breast cancer: lab findings (enzyme behavior with grape compounds) do not translate to personal risk reduction; alcohol increases breast cancer risk.
  • Observational claims (olive oil + vegetables reducing wrinkles) reflect associations, not causation; confounding factors matter.
  • What we need: well-conducted human studies, ideally trials, to establish causation.

Observational vs Experimental Evidence

  • Observational studies: snapshot associations; prone to confounding (socioeconomic status, lifestyle).
  • Trials (randomized, controlled) are the gold standard for establishing causation.

Trials, Randomization, and Placebo

  • A well-designed trial compares a new treatment to the best available alternative, not just to nothing.
  • The fish oil trial (3{,}000 children) lacked a proper control group and was vulnerable to placebo effects and natural maturation.
  • Placebo effect: beliefs and expectations can change outcomes; two sugar pills can outperform one; even a saltwater injection can outperform a dummy pill.
  • Trials must be properly controlled to attribute effects to the treatment.

Distortion Tactics in Evidence Communication

  • Media and marketers can distort evidence; misreport, cherry-pick, or oversimplify.
  • Industry trials use similar tricks with slightly more sophistication, but still aim to shape outcomes.
  • Key idea: control groups, appropriate comparators, and realistic dosing are essential for fair trials.

Publication Bias and Missing Data

  • Industry-funded trials are more likely to report positive results, but negative data are often missing.
  • The missing data problem skews the apparent effectiveness of treatments.
  • A top-priority problem: having access to all trial data is essential for accurate judgments.

Detecting Missing Data and Bias

  • Funnel plots: graphs that show trial size vs. effect; asymmetry suggests publication bias or missing small negative trials.
  • Data withholding can be inferred from statistical patterns or stories of withheld trials.
  • Reboxetine example: 76% of trials were withheld from clinicians and patients.

Data Transparency and Ethics in Medicine

  • About half of antidepressant trial data have been withheld historically; similar issues exist with other medications.
  • The Nordic Cochrane Group and European agencies have struggled to obtain complete data for systematic reviews.
  • Tamiflu data access illustrates large-scale implications for policy and public health.
  • Ethical problem: decisions cannot be made without all information.

The Right Standard: Sunshine as Disinfectant

  • Sunlight (data transparency) is the best disinfectant for science.
  • Problems persist due to a culture of tediousness around data sharing.
  • Actionable takeaway: promote full data availability and rigorous, independent analysis to improve real-world decisions.

Takeaways for Quick Recall

  • Epidemiology helps verify real-world health claims beyond sensational headlines.
  • Prioritize evidence over authority; seek randomized, placebo-controlled trials with appropriate comparators.
  • Be wary of observational studies and confounding factors.
  • Recognize and account for placebo effects in trial design.
  • Be vigilant about publication bias and data withholding; demand complete data access.
  • Use transparency and independent reviews (e.g., Cochrane-style analyses) to inform decisions.