Development of a Vitamin B12 Deficiency Patient-Reported Outcome Measure for Clinical Practice and Research

BACKGROUND

It is difficult to recognize vitamin B12 deficiency and to evaluate the effect of B12 treatment due to a broad range of variable clinical symptoms overlapping with other diseases and diagnostic biomarkers that quickly normalize during treatment. This poses a risk of delay in diagnosis and a challenge to uniformly monitor the effect of B12 treatment. There is a need for a new clinical outcome measure suitable for clinical practice and clinical evaluation studies.

OBJECTIVE

To develop a Patient-Reported Outcome Measure (PROM) which measures the severity of vitamin B12 deficiency symptoms.

METHODS

The B12 PROM was developed by (1) gathering input from experts and literature review to define a construct and develop a conceptual model, (2) processing input from health care providers, scientists, and patients to develop items and response options, and (3) improving items based on the feedback from laypersons, test interviews, semi-structured cognitive interviews with patients, and forward and backward translation (ENG-NL).

RESULTS

The B12 PROM includes 62 items grouped into 8 categories of symptoms related to vitamin B12 deficiency (General, Senses, Thinking, In limbs and/or face, Movement, Emotions, Mouth & Abdomen, Urinary tract & Reproductive organs). Cognitive interviews demonstrated good comprehensibility and comprehensiveness.

CONCLUSIONS

This study is the first step in the development of a disease-specific PROM for vitamin B12 deficiency to measure the burden of symptoms. Further validation and reliability testing are necessary before the PROM can be applied in clinical practice and research.

Effect of genetic polymorphisms involved in folate metabolism on the concentration of serum folate and plasma total homocysteine (p-tHcy) in healthy subjects after short-term folic acid supplementation: a randomized, double blind, crossover study

Data on the effect of combined genetic polymorphisms, involved in folate metabolism, on the concentration of serum folate after folic acid supplementation are scarce. Therefore, we investigated the impact of seven gene polymorphisms on the concentration of serum folate and p-tHcy in healthy subjects after short-term folic acid supplementation. In a randomized, double blind, crossover study, apparently healthy subjects were given either 0.8 mg folic acid per day (n = 46) or placebo (n = 45) for 14 days. The washout period was 14 days. Fasting blood samples were collected on day 1, 15, 30 and 45. Data on subjects on folic acid supplementation (n = 91) and on placebo (n = 45) were used for the statistical analysis. The concentration of serum folate increased higher in subjects with higher age (53.5 ± 7.0 years) than in subjects with lower age (24.3 ± 3.2 years) after folic acid supplementation (p = 0.006). The baseline concentration of serum folate in subjects with polymorphism combination, reduced folate carrier protein, RFC1-80 GA and methylenetetrahydrofolate reductase, MTHFR677 CT+TT, was lower than RFC1-80 AA and MTHFR677 CT+TT (p = 0.002). After folic acid supplementation, a higher increase in the concentration of serum folate was detected in subjects with polymorphism combination RFC1-80 GA and MTHFR677 CC than RFC1-80 GG and MTHFR CT+TT combination (p < 0.0001). The baseline concentration of plasma total homocysteine (p-tHcy) was altered by combined polymorphisms in genes associated with folate metabolism. After folic acid supplementation, in subjects with combined polymorphisms in methylenetetrahydrofolate dehydrogenase, MTHFD1-1958 and MTHFR-677 genes, the concentration of p-tHcy was changed (p = 0.002). The combination of RFC1-80 and MTHFR-677 polymorphisms had a profound affect on the concentration of serum folate in healthy subjects before and after folic acid supplementation.

Comparison of two methods for measuring methylmalonic acid as a marker for vitamin B12 deficiency

BACKGROUND

Methylmalonic acid (MMA) is a functional marker of vitamin B12 status and a valuable diagnostic tool. The gas chromatography mass spectrometry (GCMS) MMA assay has been used for decades in clinical studies.

METHODS

In this study, we compared a newly developed liquid chromatography tandem mass spectrometry assay for MMA (ClinMass® Complete Kit) with the GCMS method and further measured other relevant vitamin B12 markers (homocysteine, total B12 and holotranscobalamin) to validate the new liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) method. For this purpose, 138 samples that were sent to our routine laboratory total B12 assay were used.

RESULTS

The GCMS and LC-MS/MS assays showed a strong correlation (r=0.92, p<0.001) particularly at low holoTC levels (deficiency is more probable). Forty six cases had MMA>300 nmol/L with both methods. Only five subjects showed MMA GCMS>300 nmol/L, but MMA LC-MS/MS≤300 nmol/L. However, the LC-MS/MS method showed a slightly better correlation with other B12 markers (holoTC, total B12). In addition, the LC-MS/MS method offers several advantages over the GCMS method, such as saving time and costs, precision, flexibility and popularity in modern labs.

CONCLUSIONS

The new LC-MS/MS assay for MMA showed an excellent correlation to the GCMS method. The two methods showed similar agreements with other vitamin B12 markers.