Durability of improvement achieved in a clinical trial. Is compliance an issue?

The effects seen in clinical trials may not translate to actual practice situations. We examined the persistence of blood pressure effects 31 months after a clinical trial of treatment with hypotensive agents.

Nineteen previously untreated middle-aged men with hypertension had their office and ambulatory blood pressure recorded after 4 weeks of placebo treatment, 4 weeks of active treatment in a clinical trial, and 31 months of treatment in clinical practice. All recording was done by the same physician (IE).

Mean 24-hour blood pressure was 138/92 mm Hg after 4 weeks of placebo treatment, 128/85 mm Hg after 4 weeks of active treatment in the clinical trial, and 136/87 mm Hg after a mean of 31 months of treatment in clinical practice. The corresponding blood pressure values > or =140/90 mm Hg during the daytime were 47%, 24%, and 39%, and office blood pressures were 155/101, 145/93, and 150/91 mm Hg. Individual comparison revealed that 6 of the 19 patients had higher mean 24-hour blood pressure after several months of treatment in clinical practice than after 4 weeks of active treatment in the clinical trial.

In our study, the significantly reduced blood pressure in the clinical trial did not persist when followed up in clinical practice. At follow-up, one third of the patients had blood pressure values similar to those before active treatment. The reason for this is unclear, but inconsistent compliance may play a part in the lack of durability of the improvements. Our results indicate that effects seen in short-term clinical trials may not translate to long-term benefits in clinical practice.