[1] Univ Manchester, Sch Nursing Midwifery & Social Work, Manchester M20 3RA, Lancs, England
[2] Manchester Acad Hlth Sci Ctr, Manchester, Lancs, England
[3] Cent Manchester Fdn Trust, Manchester, Lancs, England
[4] Univ Calif San Francisco, Sch Med, Sch Nursing & Epidemiol & Biostat, San Francisco, CA USA
[5] Hong Kong Polytech Univ, Hong Kong, Hong Kong, Peoples R China
[6] Hong Kong Adventist Hosp, Hong Kong, Hong Kong, Peoples R China
[7] Washington State Univ, Coll Nursing, Spokane, WA USA
[8] Linkopings Univ, Dept Social & Welf Studies, Norrkoping, Sweden