A cross-sectional meta-research analysis of 5,851 registered hypertension trials on ClinicalTrials.gov found that timely results reporting — defined as submission within 365 days of primary completion — occurred in just 9.1% of cases (95% CI: 8.3–9.9%). Overall, only 28.8% of trials ever reported results at any timepoint. Reporting rates stratified sharply by regulatory obligation: FDA-applicable trials confirmed by flag achieved 36.9% timely reporting, while non-applicable trials reached only 6.3%. Having a U.S. trial site was the strongest predictor of timely reporting (OR 4.03). Among unreported trials, fewer than 8% had sponsor-linked publications under strict criteria.
This finding exposes a systemic transparency failure in one of cardiovascular medicine's highest-burden disease areas — hypertension affects roughly 1.3 billion adults globally and remains a leading modifiable risk factor for stroke and heart failure. Delayed or absent results reporting distorts the evidence base clinicians use to guide treatment, enables publication bias, and may allow ineffective or harmful interventions to persist undetected. The stark gap between legally obligated trials (36.9%) and the broader trial pool (9.1%) suggests regulatory pressure works, but only partially and selectively. Critically, this is a preprint not yet peer-reviewed, so methodology and conclusions may be refined. The study's cross-sectional design cannot assess whether unreported results eventually appear in journals at scale. Still, the finding is confirmatory of well-documented global trial reporting failures and strengthens calls for enforcement of the FDAAA 801 mandate and international equivalents.