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 |