This is, we believe, the first study to assess prevalence of skin problems in the legs of patients awaiting, and patients who have had, bariatric surgery. This study confirms the clinical observation that morbidly obese people have a high prevalence of skin problems in their legs. Over three quarters (n=91, 77.8%) of the people in the combined Obesity Clinic and Pre-Surgery Recall groups reported having at least one obesity-related leg problem, with 36 (31%) reporting having an ulcer. This is much higher than the prevalence of ulcers in the normal population, which ranges from 0.06% to 2% in the overall population, and exceeds 4% in those over the age of 65 [10
A major finding in this study is the observation that the prevalence of obesity-related skin problems was markedly lower in the Post-Surgery group, in comparison to the Obesity Clinic and Pre-Surgery Recall group. It may be inferred that bariatric surgery appears to be a factor in resolving skin changes that are often seen in the morbidly obese. Whether this is an effect that can be attributed to significant weight loss following surgery is not discoverable from our study.
However, given that improvements in skin changes were seen 10 to 36 months following surgery, when maximal weight loss is expected to be achieved (reflected in the average decrease in weight in the Post-Surgery group by 54.8 ± 20.9 kg), it may be that these improvements occur as a result of weight loss. Indeed, a study investigating the basis of CVI in obesity has shown that the decrease in femoral vein flow and increase in femoral vein diameter that is seen in obese individuals, is replicated consistently by increasing intra-abdominal pressure in lean adults [11
]. This suggests that high intra-abdominal pressure being transmitted to lower limb veins may be a component of the venous hypertension (and consequent skin problems in the lower legs) that is seen in obesity. Following on from this is that weight loss occurring after bariatric surgery leads to decreased intra-abdominal pressure, leading to decreased venous hypertension in the lower limb by improving femoral vein outflow, and the improvement in lower leg skin problems. Other studies investigating the link between obesity and lower limb symptoms have shown that obesity itself, separate from its link to CVI, plays a major role in the development of lower limb ulceration [12
]. In addition, a reduction in calf muscle pump function, and popliteal vein compression, particularly in the setting of obesity, have also been demonstrated to contribute to lower limb skin changes [13
]. These studies support the postulated mechanism that a reduction in obesity following bariatric surgery may directly affect lower limb skin changes.
Because bariatric surgery potentially deals with the underlying pathology of skin changes, it is expected that it prevents recurrence of the skin problems-a definite benefit as they are often difficult to treat by conventional means using dressings, medications and compression stockings, and often recur. However, there is no current literature documenting the long- term effect of bariatric surgery on recurrence of lower leg skin problems.
The prevalence of varicose veins appears to be increased in the Post-Surgery group, compared to the Obesity Clinic group. This was an unexpected finding; given that the underlying presumed venous insufficiency that is potentially improved by bariatric surgery should in theory also decrease the prevalence of varicose veins, which is caused by the same underlying process. It may be that varicose veins that are already present become more visible as the patient loses weight. One way to investigate this further would be to perform duplex ultrasounds on the legs of obese individuals, to determine the sonographic prevalence of varicose veins in these individuals as compared to self-reporting by patients.
Ongoing treatment for obesity-related skin problems are a burden on the health system. The lower prevalence of those receiving treatment in the Post-Surgery group in our study, coupled with the observation that bariatric surgery seems to improve skin changes, suggests that in the long run, bariatric surgery may prove to be the cost-effective way to treat lower limb skin changes that occur with obesity.
One of the limitations of the study is the retrospective component of the Pre-Surgery Recall group, potentially leading to recall bias, as patients were asked to recall symptoms from up to 36 months prior to the study. It may be that patients in the Pre-Surgery Recall group were recalling ever having had an ulcer in the years leading up to surgery, compared to the Obesity Clinic group that had to state if they were currently having an ulcer at the time of filling out the questionnaire (not taking into account if they had an ulcer in the past). This may explain the differences in the prevalence of some of the individual symptoms between the Pre-Surgery Recall and the Obesity Clinic groups. Alternatively, selection bias may account for the differences, reflecting the greater likelihood of patients with more severe obesity-related symptoms being selected for surgery. Another limitation is the modest number of participants in the study. Even so, the differences were marked and achieved statistical significance.
This study investigated the prevalence of self-reported skin problems in the legs of morbidly obese patients and the impact of bariatric surgery. It confirmed that morbidly obese people have a high prevalence of skin problems in their lower legs. Bariatric surgery significantly lowers the prevalence of these symptoms. These findings result in the conclusion that bariatric surgery helps in the resolution of lower leg skin problems, particularly ulcers, in morbidly obese people, possibly by improving chronic venous insufficiency by reduction in intra-abdominal pressure and body weight