Epidemiology of Myeloproliferative Disorders in US - a Real World Analysis.

Myelofibrosis (MF), Polycythemia Vera (PV) and Essential Thrombocythemia (ET) are 3 classic BCR ABL negative myeloproliferative neoplasms. MF is comprised of both primary myelofibrosis (PMF) and those with an antecedent PV or ET (Post PV and Post ET MF, respectively). The term secondary MF (SMF) when used sometimes includes those with histologic myelofibrosis without an MPN (i.e. secondary to another myeloid neoplasm or autoimmune conditions) as well as MPN associated MF (PMF and Post PV/ET MF). Limited published epidemiology data is available on these disorders. Literature reports MF incidence in the range of 0.4–1.4 per 100000. The objective of this study was to estimate prevalence and incidence using 2 real world US health insurance claims databases.

The US IMPACT® (∼30M enrollees/year) and US MARKETSCAN (∼40M enrollees/year) were used to retrospectively identify unique patients with PMF, SMF, PV and ET between 1/1/08 and 12/31/10. These databases can track patients longitudinally over multiple years, are linked at the patient level by a unique identifier that is consistent across services, health plans, and time and shown to be representative of the US population. ICD9 CM codes were used to identify PMF, SMF, PV and ET. Any MF was defined as having a diagnosis of either PMF or SMF.

Incident cohort was constructed by selecting patients who had their first MF (or PV or ET) in 2010 confirmed by absence of diagnosis 3 years prior. Prevalent cohort was constructed by identifying patients who had MF (or PV or ET) in a given year. From the MF cohort, post ET and post PV patients were identified as those who had any ET or PV diagnosis in the calendar year prior. Primary MF was defined as PMF diagnosis alone without prior PV or ET. Annual prevalence rates were calculated for each calendar year from 2008–10. Continuous enrollment was required during the time period being evaluated. Estimates were adjusted for age distribution from census data.

About 8.5M enrollees from IMPACT and 17M from MARKETSCAN each year were included in prevalence estimates.

Mean age of MF patients was 61 years in IMPACT and 67 in MARKETSCAN. Age adjusted incidence estimates of MF were about 2.4 per 100000 per year using IMPACT database, 1.7 per 100000 per year from MARKETSCAN. There is a slight increase in MF prevalence over time: from 4.9 to 5.6 in IMPACT, 3.6 to 4.2 in MARKETSCAN. Among MF patients, about 35–40% had PMF, 10% were post-PV patients, 15% were post-ET patients and the remaining had MF arising from myelodysplastic syndrome (∼30%), lupus (∼2%) and other heme and solid tumors (∼3%).

Mean age of PV patients was 55 and 36% were female in IMPACT database. In MARKETSCAN, mean age was 58 with 35% being female. Using IMPACT, annual age adjusted prevalence for PV was 57 cases per 100000. Estimates using MARKETSCAN varied from 45 to 48 cases per 100000. Age adjusted incidence of PV ranges from 22 to 27 cases per 100000 patients per year.

Mean age of ET patients was 53 and 57 years in each database. In both, 67% of patients were female. Using US IMPACT, annual age adjusted prevalence for ET was 54 to 56 cases per 100000. Estimates using MARKETSCAN varied from 39 to 44 cases per 100000. Age adjusted incidence of ET ranges from 22 to 31 cases per 100000 patients per year.

This is the first study utilizing two large national US claims databases to estimate prevalence of MPN disorders. In the US, MF prevalence ranges from 3.6–5.7 per 100,000 patients. Incidence estimates of MF range from 1.7–2.4 per 100,000 patients. PV prevalence estimates range from 45–57 cases and ET prevalence ranges from 39–57 cases per 100,000 patients. PV tends to affect more males while ET affects more female. These data provide compelling evidence to suggest that prevalence and burden of MPN associated MF is higher than has been reported in the past. Additional research using other national databases and/or study designs is needed to substantiate these findings.

Mesa:Incyte: Research Funding; Lilly: Research Funding; Sanofi: Research Funding; NS Pharma: Research Funding; YM Bioscience: Research Funding. Mehta:Sanofi: Employment. Wang:Sanofi: Employment, Equity Ownership. Iqbal:Sanofi: Employment, Equity Ownership. Neumann:Sanofi-aventis: Employment. Zhang:Sanofi-aventis: Employment.