Morbidity risks among older adults with pre-existing age-related diseases

Abstract

Multi-morbidity is common among older adults; however, for many aging-related diseases there is no information for U.S. elderly population on how earlier-manifested disease affects the risk of another disease manifested later during patient's lifetime. Quantitative evaluation of risks of cancer and non-cancer diseases for older adults with pre-existing conditions is performed using the Surveillance, Epidemiology, and End Results (SEER) Registry data linked to the Medicare Files of Service Use (MFSU). Using the SEER-Medicare data containing individual records for 2,154,598 individuals, we empirically evaluated age patterns of incidence of age-associated diseases diagnosed after the onset of earlier manifested disease and compared these patterns with those in general population. Individual medical histories were reconstructed using information on diagnoses coded in MFSU, dates of medical services/procedures, and Medicare enrollment/disenrollment. More than threefold increase of subsequent diseases risk was observed for 15 disease pairs, majority of them were i) diseases of the same organ and/or system (e.g., Parkinson disease for patients with Alzheimer disease, HR=3.77, kidney cancer for patients with renal failure, HR=3.28) or ii) disease pairs with primary diseases being fast-progressive cancers (i.e., lung, kidney, and pancreas), e.g., ulcer (HR=4.68) and melanoma (HR=4.15) for patients with pancreatic cancer. Lower risk of subsequent disease was registered for 20 disease pairs, mostly among patients with Alzheimer's or Parkinson's disease, e.g., decreased lung cancer risk among patients with Alzheimer's (HR=0.64) and Parkinson's (HR=0.60) disease. Synergistic and antagonistic dependences in geriatric disease risks were observed among US elderly confirming known and detecting new associations of wide spectrum of age-associated diseases. The results can be used in optimization of screening, prevention and treatment strategies of chronic diseases among U.S. elderly population.

Keywords: Aging; Chronic disease onset; Comorbidity; Dependent risks; Geriatric disease; Medicare.

Figure 1

Direct dependency (i.e., increased risk of later occurring disease) in disease risks when the conditional risk of the later diagnosed diseases was significantly higher (p<0.001) than in general population. Age-specific rates of unconditional (closed circles) and conditional (open circles) rates are shown for diseases in the first lines in the inset in each plot. Conditional rates are calculated for cohorts of individuals earlier diagnosed by another disease (the second lines in each plot). Hazard ratios of the later occurred disease onset for patients with vs. without the pre-existing disease are shown in the right-upper corners. Rescaled factors are shown in the left: the true rate can be calculated by multiplying the values obtained from plot’s scale by the rescaled factor.

Figure 2

Inverse effects (or, trade-offs) in the disease risks when the conditional risk of the later occurred disease is lower than in general population. All notations are similar to those for Figure 1.

Figure 3

Age-specific rates of unconditional (closed circles) and conditional (open circles) disease rates for breast cancer and goiter. All notations are similar to those for Figure 1.

Figure 4

Age-specific rates of unconditional (closed circles) and conditional (open circles) melanoma and rheumatoid arthritis rates for Alzheimer’s disease and Parkinson’s disease patients. All notations are similar to those for Figure 1.

Figure 5

Age-specific rates of unconditional (closed circles) and conditional (open circles) chronic renal disease rates for patients of selected diseases. All notations are similar to those for Figure 1.

Figure 6

Selected age-specific rates of unconditional (closed circles) and conditional (open circles) involving diabetes mellitus. All notations are similar to those for Figure 1.