Peripheral arterial disease (PAD) is a common cause of morbidity in the general population. While numerous studies have established the efficacy of prostanoids in PAD stages III and IV, the question of the role of prostanoids as an alternative or additive treatment in patients suffering from intermittent claudication (PAD II) has not yet been clearly answered. This is an update of a Cochrane Review first published in 2004.
To determine the effects of prostanoids in patients with intermittent claudication (IC) Fontaine stage II.
For this update, the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator (TSC) searched the Specialised Register (last searched January 2013) and CENTRAL (2012, Issue 12). Clinical trials databases were searched for details of ongoing or unpublished studies. In addition, reference lists of relevant articles were checked.
Randomised clinical trials of prostanoids versus placebo or alternative ('control') treatment in people with intermittent claudication were considered for inclusion.
Data collection and analysis
Two authors independently assessed trial quality and extracted data. Primary outcomes included pain-free walking distance (PFWD) and maximum walking distance (MWD), presented as mean change in walking distance during the course of the trial (% improvement) and as final walking distance (that is walking distance, in metres, after treatment) for the prostanoid and control groups.
Eighteen trials with a total of 2773 patients were included (16 in the original review and a further two in this update). As the majority of trials did not report standard deviations for the primary PFWD and MWD outcomes, it was often not possible to test for the statistical significance of any improvements in walking distance between groups. The quality of individual trials was variable and usually unclear due to insufficient reporting information. Comparison between trials was hampered by the use of different treadmill testing protocols, including different walking speeds and gradients. Such limitations in the data and the trial heterogeneity meant it was not possible to meaningfully pool results by meta-analysis.
Four trials compared prostaglandin E1 (PGE1) with placebo; individual trials showed significant increases in walking distances with administration of PGE1 and in several trials the walking capacity remained increased after termination of treatment. Compared with pentoxifylline, PGE1 was associated with a higher final PFWD and MWD but these results were based on final walking distances rather than changes in walking distance from baseline. When PGE1 was compared with other treatments including laevadosin, naftidrofuryl and L-arginine, improvements in walking distances over time were observed for both PGE1 and the alternative treatment, but it was not possible from the data available to analyse statistically whether or not one treatment was more effective than the other.
Six studies compared various preparations of prostacyclins (PGI2) with placebo. In one study using three different dosages of iloprost, PFWD and MWD appeared to increase in a dose-dependent manner; iloprost was associated with headache, pain, nausea and diarrhoea, leading to a higher rate of treatment withdrawal. Of three studies using beraprost sodium, one showed an improvement in PFWD and MWD compared with placebo while two showed no significant benefit. Beraprost sodium was associated with an increased incidence of drug-related adverse events. Of two studies on taprostene, the results of one in particular must be interpreted with caution due to an imbalance in walking capacity at baseline.
Comprehensive, high quality data on outcomes such as quality of life, ankle brachial index, venous occlusion plethysmography and haemorrheological parameters were lacking.
Whilst results from some individual studies suggested a beneficial effect of PGE1, the quality of these studies and of the overall evidence available is insufficient to determine whether or not patients with intermittent claudication derive clinically meaningful benefit from the administration of prostanoids. Further well-conducted randomised, double blinded trials with a sufficient number of participants to provide statistical power are required to answer this question.