[1] Charite, Nursing Sci, D-13353 Berlin, Germany
[2] Islamic Azad Univ, Quchan Branch, Dept Nursing, Quchan, Iran
[3] Univ E Anglia, Fac Med & Hlth Sci, Sch Nursing Sci, Norwich NR4 7TJ, Norfolk, England
[4] Maastricht Univ, Fac Hlth Med & Life Sci, Dept Hlth Serv Res, Caphri, NL-6200 MD Maastricht, Netherlands
[5] Charite, Dept Nursing Sci, D-13353 Berlin, Germany