ATLANTA — Patients diagnosed with multiple myeloma (MM) face dramatically higher risks of infection – and that risk has grown in recent years, according to a population-based registry study in Sweden presented during the 54th American Society of Hematology Annual Meeting and Exposition.

“In this large population-based study including over 9,000 multiple myeloma patients and 35,000 matched controls, we found that bacterial and viral infections represent a major threat to myeloma patients,” reported a team of Swedish researchers led by Cecilie Blimark, MD, of the Sahlgrenska University Hospital’s Hematology Department, in Gothenburg, Sweden. “We found the risk of specific infections like pneumonia and septicemia to be over 10 times higher in patients than in controls during the first year after multiple myeloma diagnosis.”

No large population-based evaluation had been made prior to this study to assess the risk of infections in MM patients compared to the normal population. The median age of patients at diagnosis and controls was 72 years (range, 25-101 years for each group).

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At 1 year after diagnosis, 22% of myeloma patients had died from infections, Dr. Blimark noted.

Overall, MM patients had a seven-fold (HR 7.1; 95% CI, 6.8-7.4) risk of developing any infection compared to matched controls, Dr. Blimark reported.

Risk of infection is worse during the first year after diagnosis (HR 11.6; 95% CI 10.6-12.7). Male sex and older age were associated with greater elevations in infection risk among MM patients (P<0.001 for each correlation).

The increased risk of developing a bacterial infection was seven-fold (HR 7.1; 95% CI 6.8-7.4) and ten-fold for viral infections (HR 10.0; 95% CI 8.9-11.4), compared to controls.

When rates of specific infection types were analyzed, MM patients had an increased risk (P<0.05) for septicemia (HR 15.6), meningitis (HR 16.6), cellulitis (HR 3.0), osteomyelitis (HR 3.5), endocarditis (HR 5.3), pneumonia (HR 7.7), and pyelonephritis (HR 2.9). For viral infections, influenza (HR 6.1) and herpes zoster (HR 14.8) were significantly higher among MM patients than controls, the authors reported.

“The risk of infections was highest during the first year after diagnosis; the risk of bacterial infections was 11-fold (HR 11.5; 95% CI 10.4-12.7) and the risk of viral infections was 18-fold (HR 17.6; 95% CI 13.1-23.8) higher compared to controls during the first year after diagnosis,” the authors reported.

Infection risk for MM patients has increased over recent years; compared to rates for 1986-1993, MM patients had a 1.6-fold (95% CI 1.5-1.7) increase in infection risk during 1994-1999 and a 2-fold (95% CI 1.9-2.1) increase in risk during 2000-2004, Dr. Blimark noted. The infection-risk HRs for myeloma patients during these three periods were 5.7, 7.0, and 8.9.

“The effect on infectious complications due to novel drugs in the treatment of MM needs to be established and trials on prophylactic measures are required,” they concluded.