Accepted answer
Only what the 7 mg arm reported, and the denominator is that arm rather than the trial. Adverse-event tables are published per arm, so the 7 mg incidence of fatigue has its own numerator and its own denominator, and pooling it with the other arms produces a figure that describes nobody. Two further deductions before you use it. Subtract the placebo arm — fatigue occurs in people who received nothing, and the difference is the part attributable to the drug. And check whether PIONEER-1 counted events or counted participants: one participant with six episodes is one row in a participant count and six in an event count, and the two get quoted interchangeably. Nothing here is medical advice.
More usefully, the trial answers a narrower question than the headline suggests, and the narrowing is where the useful information is.
Placebo arms in this class are not nothing. Lifestyle-intervention placebo arms in the major obesity trials commonly lose two to three per cent of body weight, so an active-arm figure quoted without its comparator overstates the drug effect by roughly that much.
It helps to be literal here: a composite endpoint is only as informative as its least serious component. Where a cardiovascular composite combines death, infarction and stroke, ask which component moved, because they are not interchangeable outcomes.
Where a result is quoted from a conference abstract rather than a peer-reviewed publication, the numbers routinely move between the two. It is worth checking which one you are reading.
One qualification: absence of a signal in a trial of this size is not evidence of absence for a rare event. It is evidence that the event is rarer than the trial could detect.
If a claim cannot be traced to a named trial with a named endpoint, treat it as a claim rather than as evidence.