6 REVIEW OF THE ECONOMIC EVIDENCE FOR VITAMIN B12 TESTING
This Chapter presents a preliminary economic evaluation of vitamin B12, which is limited to a summary of the findings from studies identified through the systematic literature review. A formal modelled economic evaluation of vitamin B12 testing was not within the scope of this review.
6.1 Studies relevant to the economic evaluation of vitamin B12 testing
This Chapter sets out the findings and conclusions of the review of vitamin B12 testing – as represented by MBS item numbers 66599 and 66602 – based on the analysis of the available MBS data; evidence obtained through systematic literature review; and the information derived from the stakeholder consultations.
7.1 Current usage of vitamin B12 and/or folate testing services in Australia
Over the past 10 years, the number of claims for MBS item 66599 has more than doubled (+119%) from 282,531 in 2003/04 to 618,744 in 2012/13. Over the same timeframe the number of claims for MBS item 66602 has had an even greater increase (+307%) from 522,980 to 2,129,051. The increase in benefits paid for both items reflects the increase in claims. Benefits paid for MBS item 66599 increased from $5.7m to $12.5m (+120%), whereas benefits for MBS item 66602 increased from $19.2m to $78.5m (+309%). While total benefits increased significantly, the proportion of benefits paid to each state and territory remained relatively constant over the ten-year period. The highest proportion of benefits paid over the past ten years was in New South Wales (34% of total for 66599 and 38% for 66602), followed by Victoria (30% of total for 66599 and 28% for 66602).
To further explore geographical trends in testing, an analysis was conducted of the number of services per capita (i.e. per 100,000 population), according to the address at the time of claiming of the patient to whom the service was rendered. In 2012/13, there were 2,666 claims per 100,000 people enrolled in Medicare across Australia for item 66599 and 9,172 claims per 100,000 people for item 66602. South Australia had the highest rate of claiming for item 66599 per capita (3,635 claims per 100,000 population), while the lowest per capita rate was in the Northern Territory (762 claims per 100,000 population). For item 66602, the highest number of claims per capita in 2012/13 was for NSW and Victoria (over 10,000 claims per 100,000 population in both states), while Tasmania had the lowest (less than 4,000 claims per 100,000 population).
MBS item numbers 66599 and 66602 are claimed by both males and females; however, females had a higher number of tests at all ages, except in the youngest age category (< 5 years). Females also had a steeper increase in testing volume than males, with the largest difference between genders in the 15-24 and 25-34 year age groups. For item 66599, the number of tests being performed in people aged 45 years and over was 76% for males and 64% for females. For item 66602, 71% of claims for males were aged 45 years and over versus 60% for females. For females, testing decreased from age 65 years. Similarly, the number of tests dropped dramatically in elderly men.
For both MBS items, there was an increasein the overall number of patients tested between 2008/09 and 2012/13. However, there was very little change in the proportion of patients receiving either one test per year (92% and 90% for items 66599 and 66602, respectively), two tests per year (7.5% and 9% for items 66599 and 66602, respectively), or three or more tests per year (0.8% for item 66599 and 1.1% for item 66602). These data suggest that the majority of vitamin B12/folate testing services are being undertaken for the purposes of screening/testing rather than monitoring.
Over the five-year time period from 2008/09 to 2012/13, there were no material changes in the pattern of requesting providers. General practitioners and other medical practitioners accounted for approximately 71% and 67% of all providers requesting item 66599 and item 66602, respectively. Approximately 14% of providers requesting vitamin B12/folate testing were internal medicine consultant physicians. There was a large variety of other providers requesting services, but they each accounted for less than 4% of provider counts.
For both items, there was an increase over the period 2008/09 to 2012/13 in the overall number of providers requesting vitamin B12/folate testing. For item 66599, the majority of providers (97%) requested 100 or fewer tests per year. Approximately 2% of providers requested 101 to 200 tests, and the remaining providers requested more than 200 tests per year. There were a small number of providers (ranging from 36 to 62 per year) that requested more than 400 tests per year. Approximately 88% of the providers requesting item 66602 requested 100 or fewer tests per year. Approximately 7% of providers requested between 101 and 200 tests per year and 2.5% requested 201 to 300 tests per year. Between 2010/11 and 2012/13, more than 500 providers requested over 400 tests per year.
7.2 Clinical guidance on vitamin B12 testing
The MBS data indicates that the majority of requests for vitamin B12 testing are initiated by GPs and OMPs. However, there were no Australian guidelines identified in the literature search that provide practice advice on vitamin B12 testing. Several international guidelines relating to the use of vitamin B12 testing vary widely in their recommendations. While some recommend vitamin B12 testing as a screening tool in commonly encountered illnesses such as dementia, others suggest restricting testing to patients who have already undergone pre-test investigations (such as full blood examinations and blood film examination). There were four international guidelines that were identified on the diagnosis of vitamin B12 deficiency. The 2012 Canadian guideline by the British Columbia Medical Association and Ministry of Health does not recommend routine screening of vitamin B12 deficiency. An old (1994) guideline by the British Committee for Standards in Haematology recommended that serum B12 testing is carried out following an initial investigation (full blood count and blood film examination). A Canadian review by Andres et al. (2004) recommended that all people over the age of 65 years who are malnourished, all people in institutions or psychiatric hospitals, and all people with haematological or neuropsychiatric manifestations of vitamin B12 deficiency should have their serum vitamin B12 levels measured. Smellie and colleagues (2005) recommended that vitamin B12 testing should be conducted following proper assessment of the presence of deficiency through collection of accurate information on a patient’s medical history, medication, alcohol intake and symptoms of malabsorption. The identified guidelines on diagnosing vitamin B12 deficiency have limited evidence supporting the recommendations.
Almost all guidelines did not advise on the frequency of testing. The review by Smellie et al. (2005) advised against the repeated testing of vitamin B12 unless there is a lack of patient response to treatment or if anaemia reoccurs. This is consistent with the lack of direct evidence that vitamin B12 testing improves health outcomes. There is no moderate to high level evidence pertaining to the clinical utility of vitamin B12 testing.
Only the practice parameter, published by the American Academy of Neurology, specified a methodology for vitamin B12 measurement. This advised using serum vitamin B12 level with metabolites (MMA and Hcy) in the evaluation of vitamin B12 deficiency in all patients with distal symmetric neuropathy. None of the other guidelines described in this report specify a methodology for vitamin B12 measurement.
None of the guidelines advised on the diagnostic accuracy of the different tests used to assess vitamin B12 deficiency or advised on which metabolite is the best indicator of vitamin B12 status. This may be attributed to the lack of a gold reference standard for vitamin B12.
