Multimorbidity and healthcare utilization: A register-based study in Denmark

Background People with multimorbidity have reduced functional capacity, lower quality of life, and higher mortality rates and use healthcare resources more intensively than healthy people or those with a single chronic condition. The aim of this study was to explore associations between multimorbidity and use of healthcare services and the impact of socioeconomic status on utilization of hospitalizations and bed days. Methods The study population included all individuals aged 16 years and older who lived in the Capital Region of Denmark on January 1st, 2012. Data on chronic conditions, use of healthcare services and demographics were obtained from Danish national administrative and health registries. Zero-inflated models were used to calculate anticipated annual use of hospitalizations and bed days. Findings The study population comprised 1,397,173 individuals; the prevalence of multimorbidity was 22%. Prevalence was inversely related to educational attainment. For people with multimorbidity, utilization of hospitalizations and bed days increased approximately linearly with the number of chronic conditions. However, a steep increase in utilization of bed days was observed between five and six or more chronic conditions. An educational gradient in hospitalization rates and use of bed days was observed regardless of the number of chronic conditions. Educational attainment was strongly associated with healthcare utilization. Conclusion Multimorbidity was associated with a significant increase in utilization of all healthcare services in Denmark. In addition, a socioeconomic gradient was observed in utilization of hospitalizations and bed days.

Because data on direct costs could not be linked to the study data, we identified    The decision to use zero-inflated models was prompted by the fact that many individuals do   Among 1,397,173 individuals included in the study population, approximately half 185 (720,885; 52%) were women, the majority (927,568; 66%) had none or short education, and 186 the prevalence of multimorbidity was 22% (301,757). Table 2 shows the distribution of 187 gender, age, and educational attainment by the number of chronic conditions. The prevalence 188 of both one and two or more chronic conditions was significantly higher for women than for Mean rates of healthcare utilization among people with multimorbidity were much 215 higher than among people with no chronic conditions, by a factor of 1.73 to 9.67, depending 216 on the type of utilization (Table 3). When comparing people with multimorbidity and those 217 with one chronic condition, rates of healthcare utilization were 1.44 to 4.00 times higher for    one to six or more chronic conditions (Fig 2). Hospitalizations were more frequent in 257 individuals with shorter education, compared with those with longer education. For bed day 258 utilization (Fig 3), individuals with no education exhibited the highest estimated utilization 259 rates, regardless of the number of chronic conditions.  CI, 6.64 -6.76) for GP visits. A similar but less pronounced pattern was seen when comparing 313 multimorbid individuals to those with one chronic disease (Table 3). These results demonstrate that longer for individuals with six or more conditions. The slope of the curve for six or more conditions increases twofold to 1.84 (Fig 1B). The fact that the regression coefficient no longer explains the 328 frequency of bed days per chronic condition leads us to define individuals with six or more 329 conditions as high utilizers; they make up 0.87% of the population but account for 7.29% of bed 330 days. An earlier Danish study found that 5% of the population with chronic conditions accounted  Fig 1A shows a decline in utilization between nine and ten or more conditions. A possible 338 explanation is that individuals with a very high disease burden have higher mortality, while those 339 who survive have lower healthcare utilization than expected. Only 43 individuals had ten or more 340 diagnosed conditions, and small sample size effects may also contribute to this finding.

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Socioeconomic status 342 We found that the prevalence of multimorbidity decreased with increasing educational 343 attainment, revealing a pronounced and statistically significant inverse socioeconomic gradient.

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This is consistent with previous findings [7].

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To study the impact of multimorbidity on healthcare costs, we adjusted data for proxy costs 346 for different educational attainment groups with varying profiles in terms of age, gender, other 347 healthcare utilization and level of multimorbidity. When adjusted for these effects, as described in 348 the methods statistical section, a clear inverse social gradient in hospitalization utilization appeared 349 (Fig. 2). Adjusted hospitalization utilization decreased as the level of educational attainment 350 increased, generally irrespective of the number of chronic conditions. However, adjusted bed-day a general population-based study, our findings reflect the actual situation in a real-world setting.

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Based on register data, our study was free of recall bias and there was no loss of follow up.