Bullous Pemphigoid

Introduction

Bullous pemphigoid is an acute or chronic autoimmune skin disease, involving the formation of blisters, more appropriately known as bullae, at the space between the skin layers epidermis and dermis. It is classified as a type II hypersensitivity reaction, with the formation of anti-hemidesmosome antibodies.

Causes

In most cases of bullous pemphigoid, no clear precipitating factors are identified. Potential precipitating events that have been reported include exposure to ultraviolet light and radiation therapy. Onset of bullous pemphigoid has also been associated with certain drugs, including furosemide, and other nonsteroidal anti-inflammatory agents, captopril,penicillamine, and antibiotics.

Symptom

The most common symptom of pemphigoid is blistering that occurs on the arms, legs, abdomen, and mucous membranes. Hives and itching are also common. The blisters have certain characteristics, regardless of where on the body they form: they are often preceded by a red rash, they are large and filled with fluid that is usually clear, but may contain some blood they are thick and do not rupture easily, the skin around the blisters may appear normal or slightly red or dark, ruptured blisters are usually sensitive and painful.

Treatment

Pemphigoid cannot be cured, but treatments are usually very successful at relieving symptoms. Corticosteroids, either in pill or topical form, will likely be the first treatment your doctor prescribes. These medications reduce inflammation and can help to heal the blisters and relieve itching. However, they can also cause serious side effects, especially from long-term use, so your doctor will take you off of the corticosteroids after the blistering clears up. Another treatment option is to take medication that suppresses your immune system, often in conjunction with the corticosteroids. Immunosuppressants help, but they also put you at risk for other infections. Certain antibiotics, such as tetracycline, may also be prescribed to reduce inflammation and infection.

Statistics

Ncidence-We calculated incidences by age, categorised into 10 year age bands; sex; and calendar period. We used multivariate regression to model incidence rate ratios, adjusting for changes in age, sex structure, and calendar period over time. We applied calculated incidences for both diseases to the UK population totals for the years 2001-5 to estimate the number of new cases a year. Mortality—We identified all deaths in the two case populations and matched controls and used Kaplan-Meier techniques to calculate one year mortality and five year survival rates. We used Cox regression to compare the mortality of cases and controls, adjusting for age, sex, and calendar period. We used Nelson-Aalen plots to test the proportional hazards assumption. Office for National Statistics data—We calculated expected numbers of incident cases and deaths for both diseases by applying study rates to the Office for National Statistics population (2001-5) and comparing results with Office for National Statistics data. Sample size and power calculations—The dataset for this study contained two million person years of data. Assuming a total of 1000 cases, this study would have 90% statistical power to detect a hazard ratio for death of 2.0 or greater in cases compared with controls, at the 5% level of significance. Our cohort included 869 people with bullous pemphigoid contributing 1993 person years and 3453 matched controls contributing 9765 person years. The median age at first presentation for bullous pemphigoid was 80 (range 23-102) years , and 534 (61%) patients were women. One hundred and thirty eight people with pemphigus vulgaris contributed 380 person years, and 551 matched controls contributed 1763 person years. The median age at first presentation for pemphigus vulgaris was 71 (21-102) years, and 91 (66%) patients were women. The median length of follow-up for people with bullous pemphigoid was 1.6 (range 0-9) years, and that for pemphigus vulgaris was 2.0 (0-10.4) years. Losses to follow-up were similar in cases and controls in both diseases (by the end of year 2, bullous pemphigoid cases and controls 34% lost; pemphigus vulgaris cases 30% lost, controls 31% lost) .