Study reveals bone risks from common skin treatment

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria : * Patients aged ≥ 18 years * Patients with newly diagnosed bullous pemphigoid (BP), treated according to the national diagnostic and care protocol issued by the French Reference Center for Autoimmune Bullous Diseases in April 2016. * In patients for whom lumbar spine bone densitometry cannot be interpreted at several vertebral levels from L1 to L4 (severe lumbar osteoarthritis, history of lumbar vertebroplasty, osteosynthesis hardware), the data will be interpreted using the remaining evaluable vertebrae. If the BMD of none of the vertebrae from L1 to L4 is evaluable, only hip BMD will be interpreted. * Patients, or their legal representative, who have received written and oral information and have signed an informed consent form. * Social Security affiliation. Exclusion Criteria : * Patients receiving anti-osteoporotic maintenance treatment (zoledronic acid, risedronate, alendronate, pamidronate, ibandronate, teriparatide, denosumab, raloxifene). * Patients requiring immediate initiation of anti-osteoporotic maintenance treatment (T-score \< -3 SD at at least one site or FRAX® score above the therapeutic intervention threshold). * Patients presenting with one or more major risk factors for osteoporosis: In men and premenopausal women: newly diagnosed or radiologically confirmed vertebral fracture without an obvious traumatic or tumor-related context; personal history of a peripheral fracture occurring without major trauma; systemic corticosteroid therapy prescribed for at least three consecutive months at a dose ≥ 7.5 mg/day prednisone equivalent; prolonged hypogonadism; untreated active hyperthyroidism; hypercortisolism; primary hyperparathyroidism; and osteogenesis imperfecta. * In postmenopausal women: premature menopause \< 40 years of age; BMI \< 19 kg/m²; parental history of femoral neck fracture without major trauma in a first-degree relative; history of corticosteroid therapy for at least three consecutive months at a dose ≥ 7.5 mg/day prednisone equivalent. * Patients who have received topical corticosteroids for more than one week during the two weeks preceding inclusion.