Hospital activity before and after diagnosis of monoclonal gammopathy of undetermined significance (MGUS)


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Maxine Lamb1,Eleanor Kane1,Alexandra Smith1,Eve Roman1

1University of York, York, UK

Abstract

Background

Monoclonal gammopathy of undetermined significance (MGUS; ICD-O-3=9761/1) is a premalignant clonal disorder that progresses to myeloma at ~1% per year. Whilst MGUS is often diagnosed incidentally and other symptoms of myeloma are absent, several follow-up studies have reported relationships with co-morbidities and poor survival. Illness patterns before MGUS diagnoses have, however, not been examined in relation to those seen after diagnosis. Here we compare hospital activity of people with MGUS and patients with mature B-cell malignancies to that in the general population.

Method

The study is set within the UK’s Haematological Malignancy Research Network (HMRN, www.hmrn.org), which contains two established population-based cohorts: a patient cohort of haematological malignancies (cases), and a control cohort comprising 10 age-, sex- and area-matched individuals for cases diagnosed 01/01/2009-31/12/2015. HMRN operates with Section 251 support, and both cohorts are linked to national Hospital Episode Statistics. Inpatient and outpatient visits from five years before to three years after diagnosis were counted, excluding haematology.

Results

Over the study period, cases with MGUS (n=2,239) had significantly higher hospital activity rates compared to controls (n=22,390). Before diagnosis, monthly attendance rates per 100 persons averaged 30.6 (95%CI:30.3-30.9) among cases and 20.9 (20.9-21.0) in controls, with activity rates in the controls remaining constant over time. The difference was driven by outpatient attendances and activity in cases remained high after diagnosis. Outpatient specialties with high activity before diagnosis (including rheumatology, orthopaedics, dermatology and nephrology) were similar to those found after. This unusual pattern of activity was not seen in any other haematological malignancies or precursor conditions.

Conclusion

MGUS patients have increased hospital activity unrelated to haematology several years before diagnosis, and the pattern is sustained after diagnosis. The underpinning specialities we observed are consistent with the post-diagnostic literature. That the pattern is evident at least five years before diagnosis impacts on causal and pathogenic hypotheses.