Patients with chronic kidney disease (CKD) whose kidneys appear to be functioning well enough not to require care from a specialist are hospitalized at a much higher rate than the general population, a recent study found.
The researchers also found that while cardiovascular illnesses were known to be the most common reason for patients with CKD patients to enter the hospital, a majority of stays are for other causes, particularly genitourinary, digestive, and endocrine-nutritional-metabolic illnesses, according to the study, published in PLoS Medicine.
Among kidney function tests, high levels of protein in the urine were observed to have the largest association with hospitalizations, the study also found.
Authors based their findings on a comparison of data from hospitalizations of patients with CKD with a nationwide hospitalization database. Data were used from 3939 adults from age 21 and older (average age 57.7) enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study from 2003-2008 at 7 clinical centers across the United States; participants were followed for nearly 10 years. They were compared against the National Inpatient Sample (NIS), which provided a cross-section of American adults from 2012.
The hospitalization rate for patients with CKD was 35.0 per 100 person years (PY) (95% CI, 34.3-35.6), with noncardiovascular rates of 23.9 per 100 PY (95% CI, 23.3-24.4) and cardiovascular-specific rates less than one-third of the all-cause rates (11.1 per 100 PY; 95% CI, 10.8-11.5). Rates were highest among those age 65 and above, non-Hispanic black participants, and those with diabetes.
The finding of higher hospitalization risk should have broad implications for primary healthcare providers since many of these patients would not be under the care of a kidney disease specialist, the study said. Fewer than 10% of individuals with estimated glomerular filtration rate (eGFR) of <60 ml/min/1.73m2 see a nephrologist.
“These findings highlight the need for developing better approaches to identifying patients at risk for severe complications of CKD and to guiding outpatient management strategies to improve outcomes in CKD,” the authors wrote.
Research has shown that up to 15%-20% of American adults suffer from CKD. Patients with CKD who are hospitalized are at higher risk of complications, including reentry to the hospital, higher death rates, longer inpatient stays, and worsening kidney function, the study noted.
The study found that the overall rates for hospitalization and for cardiovascular disease in patients with CKD were twice as high as for the general population. Findings were similar for noncardiovascular disease hospitalizations, revealing these patients of all ages are hospitalized for a broad range of causes.
The literature has shown that cardiovascular disease represents the largest cause of hospitalizations for patients with renal disease (21-32%), followed by infections (22%), and digestive diseases (9%-11%). However, that left large proportions of hospitalizations with undescribed causes. The new study found that almost 70% of hospitalizations are not due to cardiovascular disease.
The study also identified characteristics associated with increased hospitalization. They included a preserved eGFR (<60 ml/min/1.73m2), a systolic blood pressure level of > 130mmHG, and the presence of moderate to heavy proteinuria. Researchers found that proteinuria was a potent risk factor for hospitalization. Hospitalizations were high among those with even moderate levels of proteinuria. Those with the heaviest rates had higher rates of hospitalizations across a wide range of eGFR.
The study found that genitourinary causes represented a large proportion of CKD hospitalizations, including conditions related to kidney disease itself, such as acute kidney injury and chronic renal failure, as well as disorders of the urinary tract, including excess fluid in the kidney due to a backup of urine, stones, and infections. Many hospitalizations are due to endocrine and nutrition issues—such as diabetes, thyroid disorders, and nutritional deficiencies—as well as causes that could be attributed to kidney disease, including gout, fluid and electrolyte disorders, and disorders of mineral metabolism.
The study found that women with mild-to-moderate CKD experienced more overall and noncardiovascular hospitalizations but fewer cardiovascular hospitalizations, which may be related to a greater rate and severity of complications of kidney disease in women. Blacks and Hispanics had more cardiovascular hospitalization than White patients, possibly due to their rising rates of cardiovascular diseases.
Schrauben SJ, Chen HY, Lin E, et al. (2020) Hospitalizations among adults with chronic kidney disease in the United States: A cohort study. PLoS Med. Published online December 11, 2020;17(12): e1003470. doi:10.1371/journal.pmed.100347