Exploring the association between macroeconomic indicators and dialysis mortality

Abstract

Background and objectives: Mortality on dialysis varies greatly worldwide, with patient-level factors explaining only a small part of this variation. The aim of this study was to examine the association of national-level macroeconomic indicators with the mortality of incident dialysis populations and explore potential explanations through renal service indicators, incidence of dialysis, and characteristics of the dialysis population.

Design, setting, participants, & measurements: Aggregated unadjusted survival probabilities were obtained from 22 renal registries worldwide for patients starting dialysis in 2003-2005. General population age and health, macroeconomic indices, and renal service organization data were collected from secondary sources and questionnaires. Linear modeling with log-log transformation of the outcome variable was applied to establish factors associated with survival on dialysis.

Results: Two-year survival on dialysis ranged from 62.3% in Iceland to 89.8% in Romania. A higher gross domestic product per capita (hazard ratio=1.02 per 1000 US dollar increase), a higher percentage of gross domestic product spent on healthcare (1.10 per percent increase), and a higher intrinsic mortality of the dialysis population (i.e., general population-derived mortality risk of the dialysis population in that country standardized for age and sex; hazard ratio=1.04 per death per 10,000 person years) were associated with a higher mortality of the dialysis population. The incidence of dialysis and renal service indicators were not associated with mortality on dialysis.

Conclusions: Macroeconomic factors and the intrinsic mortality of the dialysis population are associated with international differences in the mortality on dialysis. Renal service organizational factors and incidence of dialysis seem less important.

Figure 1.

Theoretical framework of the different indicator groups and their hypothesized relation with the survival on dialysis through two different pathways. Considering the incidence of dialysis pathway, macroeconomic indicators may be associated with the health status of the general population in a country as well as its renal service organization. Both macroeconomic factors and the health status of the general population have been shown to be associated with the incidence of renal replacement therapy (RRT) (18). Moreover, they are likely to be associated with the characteristics of the incident dialysis population, because a higher incidence frequently goes hand in hand with the inclusion of more high-risk patients (26,28). The latter has shown to be related to mortality on dialysis (1,2,44). Considering the quality of dialysis care pathway, we hypothesized that macroeconomic indicators and the organization of renal services may directly be linked with the quality of dialysis care, something that has previously been known to be related to mortality on dialysis (10,44,45).

Figure 2.

Two-year mortality is widely distributed across the world. Distribution of 2-year dialysis survival probabilities for all patients (top panel), patients younger than 65 years at the start of dialysis as first renal replacement therapy (RRT; middle panel), and patients older than 65 years at the start of dialysis as first RRT (bottom panel).