The PACE Trial for Chronic Fatigue Syndrome (2011)

The UK's PACE trial claimed that graded exercise therapy and cognitive behavioral therapy produced a 60% recovery rate in CFS/ME patients, but independent re-analysis in 2018 revealed that the researchers had relaxed outcome thresholds mid-trial—boosting apparent effectiveness by 40 percentage points. When original criteria were reapplied, only 7% of patients recovered, a rate indistinguishable from placebo. A 2022 Cochrane review subsequently downgraded graded exercise therapy's recommendation level, confirming that the PACE trial's inflated outcomes misled clinicians for over a decade.