2013 · BMJ
Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: evaluation of recovered data from the Sydney Diet Heart Study and updated meta-analysis
Verdict
SCIENTIFIC
The study follows the scientific method and does not operate inside a theoretical framework. The verdict is scientific.
1·Study methodology · no theoretical framework
SCIENTIFIC
Follows the scientific method. No theoretical framework attached.
2·Paradigm · Basic Epidemiological Comparison
NOT APPLICABLE
No theoretical framework. The study verdict decides.
How the verdict is decided
This study does not operate inside a theoretical framework. Using hospital records, billing codes, or diagnostic names as labels on visible events is not the same as depending on that framework. The verdict is the study methodology score alone.
1·Study methodology
Did this study test its claim with methods that are independent, falsifiable, and non-circular?
SCIENTIFIC
This study claims that telling men who had survived a heart attack to replace saturated fat with safflower oil raised their death rate over the following years, from all causes, heart disease, and cardiovascular disease. All three tests pass.
Independently Verifiable
Pass
The study's variable is whether each man died, taken from death certificates and hospital records, and a death is something anyone can count without first accepting any diet theory.
Falsifiable
Pass
If the safflower oil group had died at or below the control rate, the claim of harm would have died instead, and those counts were sitting in the raw tape for anyone to tally.
Non-Circular
Pass
The groups were split by a concealed table of random numbers and the outcome was a body count, so no tool in the design was built from the answer the authors wanted.
Why
In 1966 to 1973, 458 men recovering from a coronary event were split by random number table. One group got liquid safflower oil and safflower margarine and instructions to cut animal fat. The other got no diet advice. Both got the same medical care. Nobody was sorted by any test; the sorting was a coin flip on paper. Deaths were recorded from death certificates and hospital records, stored on magnetic tape, and decades later the tape was recovered and the counts compared as randomized. The oil group died more: 17.6 percent versus 11.8 percent overall. The authors also report that the oil lowered the men's blood cholesterol, and the deaths went up anyway, so the cholesterol story failed in plain sight in the same data. Nothing in the comparison needed a theory to be visible. The oxidation mechanism offered in the discussion is speculation and was not tested here.
2·Paradigm · Basic Epidemiological Comparison
The three tests do not apply. There is no theoretical framework.
NOT APPLICABLE
Why
The method does not depend on any framework's claims. Random assignment is arithmetic, a diet instruction is a spoken instruction plus a bottle of oil, and death is a public event on a certificate. The cholesterol model supplied the prediction being tested, not the measurement, and this dataset killed that prediction in the direction it cared about: cholesterol fell in the oil group while more of them died. The paper's later talk of oxidized fat metabolites damaging arteries is a proposed story, untested by this trial, and the verdict here rests only on what the tape recorded. No paradigm's instruments sorted the men or defined the outcome, so there is nothing at this layer to score.
From the study
Deaths were assigned codes from ICD-7 (international classification of diseases, 7th revision) according to death certificates or final hospital admission records.
The intervention group (n=221) had higher rates of death than controls (n=237) (all cause 17.6% v 11.8%, hazard ratio 1.62 (95% confidence interval 1.00 to 2.64), P=0.05
As expected, increasing n-6 LA from safflower oil in the SDHS significantly reduced total cholesterol; however, these reductions were not associated with mortality outcomes