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Table 2 Summary of the results and quality assessment of the intervention 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 Intervention Effectiveness of vitamin B12 treatment on haemoglobin concentrations Quality of study*
Hughes [49] 1970 Placebo n = 19, Treatment n = 20 ≥ 65 Random sample of subjects aged ≥65 years from general practices in a town in Wales, UK. Subjects with vitamin B12 level <150 pg/mL were invited to participate in the trial. None had anaemia or evidence of vitamin B12 neuropathy and none was taking drugs that might interfere with vitamin B12 assays or anticonvulsants that might reduce the serum vitamin B12 level. Intramuscular hydroxocobalamin (1000 μg), twice in the first week, and then at weekly intervals for a further four weeks or placebo containing a matching solution of phenol red (phenylsulphonphtalein 0.075%) - 4 points
Hvas [50] 2001 Placebo n = 70, treatment n = 70 Treatment group: Median 75 (range 19-92) Placebo group: 74 (range 33-88) 140 subjects in Aarhus, Denmark, with elevated methylmalonic acid (P-MMA, 0.40-2.00 μmol/L) which had not received prior vitamin B12 treatment. Participants were enrolled between November 1998 and March 2000. Exclusion criteria: low Hb levels, low ferritin levels, TSH≥4.1 mIU/L, high creatinine levels, life-threatening disease, treatment with anticoagulants, tropical atoxic neuropathy. Weekly intramuscular injections of 1 mg cyanocobalamin (n = 70) or placebo containing 1 mL of isotonic sodium chloride (n = 70) for 1 month - 4 points
Seal [51] 2002 Placebo n = 11, oral vitamin B12 10 μg n = 10, oral vitamin B12 50 μg, n = 10 Mean age placebo 78, vitamin B12 10 μg 82, vitamin B12 50 μg 85 31 patients in two geriatric hospitals in Melbourne, Australia with subnormal serum vitamin B12 (100-150 pmol/L) discovered as part of their clinical assessment. Exclusion criteria: known neoplasm, life-threatening or terminal illness, history of malabsorption, pernicious anaemia, anaemia of other cause, prior vitamin B12 treatment or vitamin supplementation, neurological disorder other than stroke. Placebo (Australian Pharmaceutical Formulary (APF) red mixture and APF hydrobenzoate compound), 10 μg oral cyanocobalamin or 50 μg oral cyanocobalamin daily for 4 weeks - 2 points
  1. **Based on checklist from Jadad et al. [25] Higher scores indicate higher quality (range 0-5). Intervention studies that scored 3 points or more were considered 'high quality'.