Vitamin D deficiency and associated factors among cardiology patients in Nouakchott, Mauritania: A cross-sectional study using modified Poisson regression. - El Hanefi RM; Ebou MH; El Welati AE; Issa MY; Dehah CMEH; Yacouba D; Elhoumed M; El Kebir MVO (American heart journal plus : cardiology research and practice, 2026)