Research question Does pale sulphonated shale oil help to heal venous ulcers?
Answer Possibly. Pale shale oil helps to reduce the surface area of ulcers compared with compression alone but may not increase the chance of cure.
Why did the authors do the study? Pale sulphonated shale oil is an established treatment for inflammatory skin conditions such as psoriasis and eczema. Experiments in vitro and in vivo suggest the oil may have beneficial effects on wound healing. These authors wanted to test it formally as a topical treatment for venous ulcers. Venous ulcers are common and notoriously hard to treat.
What did they do? 119 German and Slovakian patients took part in a randomised controlled trial comparing compression therapy alone with compression therapy plus pale shale oil for venous ulcers. All participants had ulcers caused by chronic venous insufficiency with a surface area of at least 3 cm2. They were treated for 20 weeks with standard compression therapy plus a gel containing 10% pale sulphonated shale oil or standard compression therapy plus the vehicle (gel) only. The manufacturers of the active gel sponsored the trial, which was only single blind. The researchers who measured the surface area of the ulcers using photoplanimetry were unaware of treatment allocation.
After 20 weeks, the authors looked for differences between the groups in the size of the ulcers (relative reduction in surface area) and healing (complete epithelialisation). All analyses were intention to treat. The groups were comparable at baseline, except that patients allocated shale oil were heavier than those allocated the vehicle only.
What did they find? Venous ulcers treated with shale oil were 72% smaller at the end of the trial, shrinking from a mean of 15 cm2 to a mean of 6.2 cm2. Control ulcers shrank from a mean of 11.4 cm2 to a mean of 10.8 cm2 (P = 0.0005 for comparison with active treatment). A significant difference between the groups appeared after about six weeks' treatment and persisted until the end of the trial. Venous ulcers treated with the shale oil were also more likely to granulate and to heal completely than control ulcers, although the difference was not significant (21/62 (34%) completely healed v 13/57 (23%) in the control group, P = 0.177). Two patients in each group developed eczema and pruritis.
What does it mean? The patients in this study had large, chronic venous ulcers with an average surface area of 26 cm2 and 17 cm2 in the treatment and control groups respectively. Such ulcers can seriously affect patients' quality of life, so this study is encouraging. The authors were disappointed that the shale oil had no significant effect on the chance of complete healing. But healing rates were relatively low overall, and the trial relatively small and brief. Shale oil has anti-inflammatory and antibacterial properties, making an effect on wound healing biologically plausible. The treatment seemed safe in this trial but both the risks and benefits will need to be confirmed.
Beckert S. Efficacy of topical pale sulfonated shale oil in the treatment of venous leg ulcers: a randomized controlled, multicenter study. J Vasc Surg 2006;43: 94-100
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