Skip to main content

Table 1 Summary of the results and quality assessment of the observational studies included in this review

From: Subnormal vitamin B12 concentrations and anaemia in older people: a systematic review

Author Year of publication Sample size (N) Age of subjects (years) Study population Presence of an association between subnormal vitamin B12 and anaemia Quality of study*
Cross-sectional
Population-based
Allain [27] 1997 233 ≥60, median 72 Random sample of older Zimbabweans (rural and urban). ? 5
Björkegren [28] 2001 224 ≥70, mean 78.0 (95% CI 77.2-78.9) Random sample of persons aged 70 years and over in the Borough of Älvkarleby in the county of Uppsala, Sweden - 6
Clarke [29] 2008 2257 ≥65, mean 79.2 (SD 6.2) Oxford Healthy Aging Project: Random sample from general practice registers of people ≥65 years living in Oxford, UK. Banbury B12 Study: Random sample of people aged ≥75 years living in their own homes and registered with general practices in Banbury, Oxfordshire, UK. + 6
Hin [30] 2006 1000 ≥75, mean 81.4 (SD 4.6) Random sample of people ≥75 years living at home, registered with general practitioners in Banbury, England - 4
Hvas [31] 2005 937 Median 72, range 19-102 Subjects with increased MMA (>0.28 μmol/L) within in Aarhus, Denmark, from 1995-2000. - 5
Johnson [32] 2003 103 ≥60, mean 76.4 (SD 8.1) Older individuals enlisted in nutrition service program in rural northeast Georgia, USA. ? 4
Lippi[33] 2009 878 Range 85-101 Unselected subjects older than 85 years, who were referred by general practitioners to a laboratory in Verona, Italy, for routine diagnostic check-up over a period of 2 years - 6
Loikas [34] 2007 1048 ≥65, 37% ≥75 Lieto study; unselected population based health survey in Lieto, Finland. - 6
McLennan [35] 1973 347 >65 Random sample of people >65 years living at home in Kilsyth and Northern Glasgow, UK. ? 5
Morris [36] 2007 1459 ≥60, mean 70 (SEM 0.32) Non-institutionalized civilian population (NHANES), USA. + 5
Penninx [37] 2000 700 ≥65, mean 77.3 Physically disabled older women living in the community (Women's Health and Ageing Study), Baltimore area, USA ? 4
Hospitalized/Institutionalized
Bisbe[38] 2009 599 Mean 68 (SD 13) All consecutive patients scheduled for major orthopaedic surgery for which blood was routinely grouped preoperatively in University Hospital in Barcelona, Spain. - 5
Chui [39] 2001 3453 48% >70 All patients admitted to the Prince of Wales hospital, Hong Kong, with vitamin B12 measurements in 1996. - 5
Joosten [40] 1990 292 >65 Consecutive patients admitted to the geriatric department of the University Hospital, Leuven, Belgium ? 5
Kwok [41] 2002 96 >55, mean age >78.0 Female ambulatory vegetarians (>3 years) in Hong Kong. ? 5
Metz [42] 1996 94 Cases: mean 79.8 Controls: mean 80.7 Patients with suspected low vitamin B12 levels based on clinical examination by attending staff in Royal Melbourne and North West hospitals, Australia. If low vitamin B12: case. If normal vitamin B12: control. - 2
Mooney [43] 2004 905 65-85 Hospitalized patients in Belfast, Ireland, who had vitamin B12, folate, Hb, MCV and ferritin measured within ±4 days of each other in February-July 2003 - 3
Prayurahong [44] 1993 147 ≥60 Subjects visiting clinic for older individuals in Rajvithi Hospital, Bangkok ? 3
Stott [45] 1997 290 Range 62-110 Consecutive new referrals to a geriatric medical unit in Glasgow, Scotland. - 5
Wang [46] 2009 827 Mean 77.1 (SD 7.5), range 60-96 Patients in the department of Neurology of Shanghai Punan Hospital, Shanghai, China. + 4
Witte [47] 2004 296 Mean 72.5 (10.3) Consecutive patients with chronic heart failure attending a heart failure clinic in Cottingham, UK - 4
Longitudinal
Den Elzen [48] 2008 423 85 All 85-year-old inhabitants of Leiden, the Netherlands. Participants using vitamin B12 or folate supplements at baseline or during follow-up were excluded. - 7
  1. *Based on checklists from van der Windt et al [23, 24]. Higher scores indicate higher quality (range cross-sectional studies 0-7; longitudinal studies 0-9). Cross-sectional studies that scored 5 points or more were considered 'high quality'. Longitudinal studies that scored 7 points or more were considered 'high quality'.