Older kidney stone patients more likely to have concurrent urinary tract infection

Atlanta-Both the clinical presentation and management of incident kidney stone disease appear to vary by age such that older individuals are more likely than their younger counterparts to present with a concurrent urinary tract infection (UTI), have no or atypical pain, and require surgical intervention, reported researchers from Mayo Clinic, Rochester, MN.

Data from their study were derived from a National Institutes of Health-funded chart review of Olmsted County, MN, residents participating in the Rochester Epidemiology Project. A random sample of nearly 3,500 charts with a first-time ICD-9 code for nephrolithiasis between the years 1984 and 2003 was selected and subjected to manual review to validate incident cases of symptomatic stone disease, defined by having no prior stone diagnosis, symptoms (hematuria, UTI, and/or pain), and stone confirmation by imaging, passage, or surgery.

Only 1,590 validated first-time, symptomatic adult stone formers were identified with an age range from 18 to 96 years. The patients were divided into five age groups with the youngest including persons 18 to 29 years and the oldest representing those ages 70 years and above. Comparisons were made between age groups for differences in rates of various presenting symptoms, laboratory results, interventions, and outcomes.

"It was my impression that older patients with stone disease seemed less likely to report pain than younger individuals. This led me to hypothesize there are age-related differences in stone disease presentation, and a colleague suggested investigating it using the available database," said Dr. Krambeck, who reported the findings at the AUA annual meeting in Atlanta.

"Previously published literature reports age-related differences in stone composition, but our findings on presentation and outcomes are novel. We believe that because stone disease in older patients seems less likely to present with specific symptoms, it may be important to have a higher index of suspicion to ensure a timely diagnosis of urolithiasis in the elderly. Perhaps clinicians should also have a lower threshold for intervention for stone disease in older persons who also appear to have more morbidity associated with their stone disease."

Risk of UTI rises with increasing age

The study results showed increasing age significantly increased the likelihood of patients presenting with atypical or no pain, fever, diarrhea, pyuria, and bacteremia, while renal colic and voiding symptoms were more common among younger individuals. The risk of having UTI increased 1.26-fold per decade of life.

Increasing age was also associated with an increased likelihood of having a computed tomography scan, urologic consult, and hospitalization related to stone disease. Overall, surgical intervention was required in about one-third of the cohort, and the likelihood of having surgery increased significantly with rising age, by 1.24-fold for each decade of life. Type of surgery performed also varied by age, with younger individuals more likely to have ureteroscopy and older persons more likely to have shock wave lithotripsy, temporizing stent placement, and percutaneous nephrolithotomy.

Consistent with previous reports, there were also age-related differences in stone composition. Calcium phosphate stones were more common in younger patients and uric acid and atypical stones more likely in those aged 70 years and above. Stone size and location did not vary by age.