Impaired results of a randomised double blinded clinical trial of propranolol versus placebo on the expansion rate of small abdominal aortic aneurysms

Background, To study the propranolol treatment of small abdominal aortic an eurysms (AAA) concerning intention to treat, side effects, and inhibition o f expansion. Methods. Design: Two-year lasting prospective randomised double-blinded int ervention trial. Setting: Hospital-based mass screening for AAA with annual ambulatory control of small ARA. Participants: Of 122 screening-diagnosed small AAA, 51 (42%) were excluded because of contraindications or present b eta-blockage, and 17 refused participation. Thus, 54 (44.3%) were included. Intervention: Participants were randomised to 40 mg propranolol twice a da y or placebo. Measures: The same observed was used to follow-up AAA-expansi on, side effects, quality of life (QL), branchial and ankle blood pressure (ABI), and pulmonary function (FEV1 and FVC). Results. Sixty percent in the propranolol group, and 25% in the placebo group dropped out, mainly caused by dyspnoea in the propranolol group (RR=1.74, 95% C.I.: 1.06-2.86). Five (16.7%) died in the propranolol group, while 1 (4.2%) died in the placebo g roup (RR=1.6 (1.02-2.51)). Furthermore, decreased pulmonary function, ABI, and QL was noticed in the propranolol group, Consequently, the trial was st opped after two years. Ninety-five percent of the measurements of the AAA w ere measured within 2 mm variation. If expansion was defined as above 2 mm annually, the relative risk of expansion in the placebo group was 1.17 (0.7 4-1.85), and 2.44 (0.88-6.77) among the non-drop-outs. Conclusions. Only 22% of small screenings-diagnosed AAA were treatable with propranolol for two years. Consequently, only large scale studies are capa ble of showing potential minor inhibition of expansion by propranolol. Howe ver, whether such treatment ever becomes ethically acceptable is debatable.