HealthDay News — The costs of having two noncommunicable diseases (NCDs) is generally superadditive, according to a study published online Jan. 8 in PLOS Medicine.

Tony Blakely, M.B.Ch.B., M.P.H., Ph.D., from the University of Otago in Wellington, New Zealand, and colleagues examined the health expenditure by disease phase for NCDs in New Zealand using data for 18.9 million person-years and $26.4 billion in spending. The researchers identified persons with any type of cancer, cardiovascular disease (CVD), diabetes, or musculoskeletal, neurological, or chronic lung/liver/kidney disease. The presence of any of the 15 possible comorbidity pairings of these NCDs were identified.

The researchers found that 59 percent of health expenditure was attributable to NCDs; disease-related expenditure was generally highest in the year of diagnosis and year of death. Greater health expenditure was reported for a person with two diseases simultaneously compared with the expected sum of having the diseases separately for all 15 comorbidity pairs, apart from the CVD-cancer pair. In addition, for a person with two diseases, the excess comorbidity costs were higher at younger ages. At the population level, 23.8 percent of total health expenditure was due to higher costs of one of the 15 comorbidity pairs versus the six NCDs separately.

“We suspect that the general patterns of these results (i.e., of comorbidity impacts being superadditive) for New Zealand are likely to be generalizable to other high-income countries,” the authors write.

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