Cost Effectiveness in Low Risk MGUS Patients

Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant disorder characterized by the asymptomatic presence of a monoclonal protein. It is defined by an M protein < 3 gm/dl, less than 10% clonal plasma cells in the bone marrow, and the absence of anemia, hypercalcemia, renal insufficiency and bone lesions. In 2010 the International Myeloma Working Group (IMWG) advocated for MGUS patients to be stratified into low risk disease, which carries a 5% risk of progression to multiple myeloma at 20 years, and high risk disease, which represents a 20% risk at 20 years. This stratification model categorizes patients as low risk if they have an IgG paraprotein with an M-component < 1.5 g/dl and a normal free light chain (FLC) ratio. As such, it is suggested that the initial workup be comprised of a serum protein electrophoresis (SPEP), an immunofixation (IFE), and a FLC ratio. A bone marrow biopsy (BM) and bone survey should only be performed if anemia, hypercalcemia or an elevated creatinine of unclear etiology is noted. If these studies place a patient into the low risk, it is suggested the patient follow up at 6-months with only an SPEP. If the SPEP is stable, the next follow-up is recommended to occur at 2 to 3 year intervals unless symptoms arise suggestive of a plasma cell dyscrasia.

The risk stratification of MGUS patients was validated in 2013 by Turesson et al. in a Swedish cohort (Blood, 2014; 123:338-345). Nevertheless, the risk model is not universally accepted and unnecessary office visits along with laboratory studies are performed on low risk patients.

The purpose of this study was to perform an internal retrospective review of our patients diagnosed with low risk MGUS, evaluating excess medical costs incurred when patients were not risk stratified by the IMWG recommendations.

Methods:

MGUS patients seen in the Hematology Oncology Division of Drexel University between 2014 and 2016 were retrospectively categorized into high and low risk based on the IMWG criteria. Those determined to be low risk were evaluated over two years for extra costs incurred outside the IMWG recommendations. Extra cost was tallied based on initial workup and surveillance studies performed up to two years from diagnosis.

Costs per test and follow up visits were based on our office appointment pricing and BM biopsy charges. Laboratory costs were obtained based on pricing from ACCU reference lab.

Cost per test (varies by lab/provider)

SPEP $67

UPEP $130

Serum IFE $200

Urine IFE $72

IgA $27

IgG $27

IgM $27

K/L ratio $120

B2 microglobulin $42

Office Visit $40 - $100

Bone Survey $500 - $1200

BM biopsy $500- $1000

Results:

Sixty patients seen between 2014 and 2016 met the criteria for MGUS. Twenty-eight patients were determined to have low risk disease. Of the 28 patients, five were diagnosed prior to 2010 and were excluded. In the remaining 23 patients, four followed up at exactly six months from diagnosis and only one had an SPEP. The most common test ordered was quantitative immunoglobulins (QI) aside from a CBC and CMP. The total number of excess office visits was 49. Three patients had unnecessary BM biopsies (total cost $1,000 - $2,000), and 11 had unnecessary bone surveys (Total $5,500 - $13,200). The total cost of unnecessary lab tests within 2 years was $6,024 and the total cost of unnecessary office visits within 2 years was $1960 - $4900. Thus, the average excess spent per patient was $630 - $1135, for a total excess cost for the 23 patients of $14,484 - $26,124.

Conclusion:

This internal review highlights the excess medical costs incurred when patients are not risk stratified by the IMWG recommendations. Ideally, no further health care dollars should be spent for low risk MGUS patients who have a stable SPEP at the 6-month visit until the 2 or 3 year follow up visit. The actual excess amount spent in our office in 2 years for these patients was $14,484 - $26,124 beyond the cost of the standard of care recommended by the IMWG guidelines. Additionally, these values did not include excess basic labs such as a CBC or CMP and it did not include extension of our investigation out to three years which would result in further unnecessary costs. One patient was noted to accumulate excess cost due to his co-morbid condition of prostate cancer, which led to increased surveillance for his low risk MGUS. The risk stratification model allows physicians to offer patients a better understanding of their disease, decrease the patient's burden and reduce the cost on healthcare.