Table 2.

Summary of reported cases of association between skin and bone diseases.

References	Skin disease	Bone disease	Study design	Cases	Main results	Possible causes
Wi et al. (52)	Psoriasis	Osteopenia, osteoporosis, pathological fractures	Literature review	13 studies	Association with osteoporosis: yes 10, no 3 Inconsistent (because of small sample sizes and missing patient information): Patients with extensive psoriasis with a longer duration of psoriasis are at increased risk of osteopenia and osteoporosis.	Systematic corticosteroids, low vitamin D levels, less physically active
Ogdie et al. (53)	Psoriasis and PsA	Pathological fractures (vertebrae, hip)	Longitudinal cohort study	Psoriasis (n = 158,323), PsA (n = 9,788) aged 18–89	PsA: all fracture aHR 1.26 (1.06–1.27), mild psoriasis: all fractures, vertebral and hip fracture: aHR 1.07 (1.05–1.10), 1.17 (1.03–1.33) and 1.13 (1.04–1.22), severe psoriasis; all fracture and vertebral fracture: aHR 1.26 (1.15–1.39) and 2.23 (1.54–3.22).	Increased prevalence of risk factors for osteoporosis and fracture (e.g., diabetes, alcohol abuse, smoking, depression, antidepressant use, corticosteroids, methotrexate, and ciclosporin)
Shalom et al. (51)	Chronic urticaria	Osteoporosis	A longitudinal, community-based cohort study	Chronic urticaria (n = 11,944)	The adjusted multivariate analysis demonstrated that chronic urticaria was significantly associated with a higher risk for osteoporosis (HR 1.23, 95% confidence interval 1.10–1.37, p < 0·001).	Increased mast cell numbers are associated with increased bone resorption and decreased bone formation. Female sex, systemic corticosteroids, chronic inflammation
Silverberg (54),	Atopic Dermatitis	Low BMD	Cross-sectional study	3,049 children and adolescents aged 8–19 years old	Lower BMD z-score for the total femur (survey linear regression; adjusted β [95% CI]: −0.42 [0.68 to −0.16]), including trochanter (−0.29 [−0.54 to −0.05]) and femoral neck (−0.29 [−0.53 to −0.05]) and total lumbar spine (−0.31 [−0.52 to −0.11]).	Higher levels of IgE, WBC counts levels, and higher odds of 25-OH vitamin D deficiency, low calcium and alkaline phosphatase, dietary restrictions
Wu et al. (55)	Atopic dermatitis	Low BMD, osteopenia, osteoporosis, related fractures	Systematic review and meta-analysis	10 studies, children and adolescents and adults, Study participants ranged from 29 to 61,065,660	Adults: atopic dermatitis (OR [95% CI], p-value) fracture (1.13; [1.05–1.22]; p = 0.001) Atopic dermatitis; osteoporosis (1.95; [1.18–3.23]; p = 0.009), osteopenia (1.90; [1.51–2.38]; p < 0.001)	(1) Inflammation-induced bone loss, (2) low vitamin D levels, (3) Corticosteroids, (4) Dietary restrictions, (5) Less physical activity, (6) Depression, stress, anxiety, and sleep disturbance, (7) Obesity, cardiovascular disease, and high alcohol and tobacco consumption
Chovatiya and Silverberg (56)	Bullous disease (pemphigus and pemphigoid)	Osteopenia, osteoporosis, osteomalacia, pathological fractures	Cross-sectional study	Pemphigus (n = 4,506) pemphigoid (n = 8,864)	Pemphigus;(adjusted OR [95% CI]) Osteopenia (2.20 [1.59–3.05]), osteoporosis (2.54 [2.16–2.98]), osteomalacia (29.70 [4.05–217.83]), fractures (2.04 [1.42–2.91]) Pemphigoid; (adjusted OR [95% CI]) Osteopenia (1.59 [1.06–2.41]), osteoporosis (1.38 [1.18–1.63]), fractures (1.26 [1.04–1.53])	Systematic and topical corticosteroids, inflammation-induced bone loss, less physical activity, low vitamin D levels
Hsu et al. (57)	Bullous disease (pemphigus)	Osteopenia, osteoporosis	Case–control study	Pemphigoid (n = 130), age/sex-matched controls (n = 390)	Pemphigoid; (adjusted OR [95%CI]) osteopenia;10.07 [3.72–27.25], osteoporosis;4.19 [1.50–11.73]	Systematic corticosteroid

Ref, reference; PsA, psoriatic arthritis; PTH, parathyroid hormone; OP, osteoporosis; BMD, bone mineral density; aHR, adjusted Hazard Ratio; OR, Odds ratio; CI, confidence intervals.