Payer Type, Race/Ethnicity, and the Timing of Surgical Management of Urinary Stone Disease

PURPOSE

Surgery for upper tract urinary stone disease is often reserved for symptomatic patients and those whose stone does not spontaneously pass after a trial of passage. Our objective was to determine whether payer type or race/ethnicity is associated with the timeliness of kidney stone surgery.

MATERIALS AND METHODS

A population-based cohort study was conducted using the California Office of Statewide Health Planning and Development dataset from 2010 to 2012. We identified patients who were discharged from an emergency department (ED) with a stone diagnosis and who subsequently underwent a stone surgery. Primary outcome was time from ED discharge to urinary stone surgery in days. Secondary outcomes included potential harms resulting from delayed stone surgery.

RESULTS

Over the study period, 15,193 patients met the inclusion criteria. Median time from ED discharge to stone surgery was 28 days. On multivariable analysis patients with Medicaid, Medicare, and self-pay coverage experienced adjusted mean increases of 46%, 42%, and 60% in time to surgery, respectively, when compared with those with private insurance. In addition, patients of Black and Hispanic race/ethnicity, respectively, experienced adjusted mean increases of 36% and 20% in time to surgery relative to their White counterparts. Before a stone surgery, underinsured patients were more likely to revisit an ED three or more times, undergo two or more CT imaging studies, and receive upper urinary tract decompression.

CONCLUSIONS

Underinsured and minority patients are more likely to experience a longer time to stone surgery after presenting to an ED and experience potential harm from this delay.

Composition of urinary tract stones formed by children in two populations in the Uyghur region of China

BACKGROUND

To retrospectively compare the composition of urinary tract stones formed by Uyghur children from the southern (Kashgar) and northern (Urumchi) parts of the Xinjiang region.

METHODS

The chemical composition of urinary tract calculi formed by 855 Uyghur children from the two regions in Xinjiang (366 Kashgar and 489 Urumchi) was compared retrospectively. Stone composition was determined by infrared spectroscopy. Factors that might have been of relevance for the findings such as age, gender, stone location and geographic region were also considered.

RESULTS

Kashgar children were younger than Urumchi children (2.8 ± 2.7 vs. 4.3 ± 3.7 years, p < 0.001). Although ammonium urate was the dominant stone component in the whole population, calcium oxalate was most common in children from Urumchi. The mean occurrence of ammonium urate, calcium oxalate and uric acid differed significantly between stones formed by Kashgar and Urumchi children (52.5% vs. 29.2%, 18.9% vs. 29.4%, 12.3% vs. 20.9%; respectively, p < 0.001). Renal stones were less frequently recorded in Kashgar children than in Urumchi children (65.8% vs. 91.6%, p < 0.001). Interestingly, bladder stones were more common in children from Kashgar (28.4% vs. 3.7%; p < 0.001).

CONCLUSION

Uyghur children from the southern part of Xinjiang apparently had a more serious form of stone disease than children from the northern part and the occurrence of stones dominated by ammonium urate stones was extremely high in children from the southern part of the region.

Cystinuria: the South Indian experience

Cystinuria is reportedly a rare condition affecting the stone patients in India. This paper presents the occurrence of cystine-related abnormality in the population of stone patients reporting to the hospitals in South India. Two thousand and eight hundred urine samples from 1,300 patients attending the urinary stone clinic during the period 2004-2008 were assessed for cystinuria by performing the nitroprusside test on the early morning urine and random samples on the day of attendance. Urinary deposits were also studied in all the patients. Stones retrieved from 800 stone patients were analysed qualitatively and by Fourier Transform infra red (FTIR) spectroscopy. Cystinuria was identified in only three patients. None of these patients showed cystine crystals. Three other patients out of the 1,300 showed presence of cystine crystals in the urine deposit. FTIR spectroscopy of the stones retrieved from the patients showed presence of cystine in 19 out of the 800 stones analysed (2.375%). None of the patients with cystine in the stones had either cystine crystals in the urine or positive nitroprusside test for cystine. All the patients who had positive cystine, cystine crystals or cystine in stone analysis had other biochemical abnormalities. They were medically managed with appropriate biochemical corrective chemotherapy and had control of stone disease process. All the patients were advised purine restriction in the diet. It is concluded from the study that cystinuria is a rare entity in South India. It, however, exists in a small percentage of stone patients. Specific treatment with D-penicillamine was not administered to the patients in view of the high cost, nonavailability and possible toxicity. The patients considered above did not have intractable stone disease which was not amenable to usual modalities of directed medical therapy.

Renal response to lithogenic and anti-lithogenic supplement challenges in a stone-free population group

OBJECTIVE

In South Africa, urolithiasis is extremely rare in the black population, but is common in the white population. The objective of this study was to investigate the individual effects of 5 different dietary and supplemental challenges (high dietary calcium, calcium supplement, vitamin B6 supplement, L-glutamine supplement, and L-cysteine supplement) on the urinary risk factors for calcium oxalate urolithiasis in subjects from both race groups.

DESIGN

Complete Latin Square design.

SETTING

University research laboratory.

SUBJECTS

Subjects were recruited from the student cohort of the University of Cape Town (10 male subjects from each race group). Selection criteria were no history of renal or metabolic diseases, and no chronic or acute medication. Subjects served as their own controls.

INTERVENTION

After 7 days on a self-selected standardized diet, a 24-hour baseline urine sample was collected. A second 24-hour urine sample was collected after 5 days on the prescribed dietary or supplemental challenge. These were analyzed for biochemical and physicochemical risk factors. Additionally, 24-hour dietary recall questionnaires were recorded at baseline and after the 5-day test period, and were analyzed using a food analysis program. Statistical analysis of variance was performed on all of the data.

MAIN OUTCOME MEASURES

Urine composition, relative supersaturation of urinary salts, calcium oxalate metastable limit, and Tiselius risk index.

RESULTS

None of the protocols altered any of the urinary biochemical or physicochemical risk factors in black subjects. In white subjects, the calcium diet significantly increased urinary potassium (P =.0001) and decreased the relative supersaturation of brushite (P =.035); the calcium supplement significantly decreased the Tiselius risk index (P =.014); vitamin B6 supplement significantly decreased urinary calcium (P =.016), urinary phosphate (P =.027), and the relative supersaturation of brushite (P =.004); L-glutamine supplement significantly decreased relative supersaturation of calcium oxalate (P =.01); L-cystine supplement significantly decreased urinary calcium (P =.031) and the Tiselius risk index (P =.013).

CONCLUSIONS

Because none of the challenges had an effect on the urinary risk factors in black subjects, it is speculated that a renal or gastrointestinal homeostatic adjustment occurs in this group, thereby keeping urinary concentration of substances in balance.

Urethral calculi: presentation and management

OBJECTIVE

To determine the occurrence, symptoms, treatment and outcome in patients with urethral stones.

PATIENTS AND METHODS

Fifty-one consecutive patients with urethral calculi were assessed prospectively; all were male and one was an infant.

RESULTS

Acute retention of urine occurred in 78% of patients, urethral anatomical pathology in 6% and posterior urethral calculi in 88%. The urethral stones, solitary in each patient, consisted of calcium oxalate in 86%, struvite in 6%, mixed stones in 4%, calcium phosphate in 2% and uric acid in 2%. A methodical approach to therapy was used which aimed to clearly define the circumstances in which a given procedure was used, and the resulting success rate.

CONCLUSION

The common belief that most urethral calculi in patients in developing countries originate from the bladder does not seem to be generally applicable. Urethral anatomical pathology does not seem to be a necessary condition for most of these calculi.

Relationship among risk factors for nephrolithiasis, cardiovascular disease, and ethnicity: focus on a law enforcement cohort

This cross-sectional study determined the prevalence of nephrolithiasis and common cardiovascular disease (CVD) risk factors in a law enforcement officer (LEO) cohort and evaluated the relationship of nephrolithiasis with several CVD risk factors, including the possible effect of ethnicity. Self reported nephrolithiasis and CVD risk factors among currently employed male LEOs from nine states (n = 2,818) were compared to other men in the same states (n = 9,650). Of the LEOs, 6.2% (n = 174) self reported at least one kidney stone (range = 1 to 12, mean 2.3 6 2.1 stones). Twenty five percent of Native American LEOs (n = 7 of 28) self reported a history of stones. In LEOs with a history of nephrolithiasis, overweight defined as body mass index . 25 kg/m2 (odds ratio [OR] = 1.80, 95% confidence interval [CI] = 1.04, 3.11), hypercholesterolemia (OR = 1.53, 95% CI = 1.09, 2.15), and hypertension (OR = 1.46, 95% CI = 1.02, 2.11) were associated with the disease. These results suggest officers with common CVD risk factors are also at an increased risk for nephrolithiasis. Native American LEOs have a disproportionately higher prevalence of nephrolithiasis than do other ethnic groups.

Unique pattern of urinary tract calculi in Australian Aboriginal children

Young Aboriginal children in remote regions of tropical and desert Australia are at risk of developing urate stones in their upper urinary tract from an early age. These radiolucent calculi were only recognized with the availability of ultrasound diagnosis and are not associated with anatomic anomalies or abnormal uric acid production/metabolism. Although these stones appear to resolve spontaneously after the weaning period, some result in ureteric obstruction and infection which may lead to renal damage. This pattern of urolithiasis differs from the usual global urolithiasis pattern of either endemic bladder stones in young children in developing countries or predominantly calcium-based stones in upper tracts of older children and adults in affluent industrialized countries, where upper tract urate stones account for only a minority of childhood urinary tract stones. Risk factors for urate stones are low urine output and acidic urine. An association between urolithiasis and carbohydrate intolerance leading to chronic acidosis has been suggested for Aboriginal children, but existing limited evidence does not support this as a major aetiological factor. Although further studies on the epidemiology, natural history and management of these urate stones are needed, we believe the focus should be on improving the known social and environmental risk factors of remote Aboriginal children during the weaning period which contribute to the unacceptably high prevalence of failure to thrive, diarrhoeal disease, environmental enteropathy, iron deficiency and urolithiasis.

Lithogenic risk factors in normal black volunteers, and black and white recurrent stone formers

OBJECTIVE

To compare lithogenic risk factors in normal black volunteer men (BN), male black stone formers (BSF) and male white recurrent stone formers (WSF); in addition, the differential diagnoses in the stone formers were compared to determine if the causes of renal stones differed in the two groups.

SUBJECTS AND METHODS

The study included 22 BN, 22 consecutive BSF and 122 consecutive WSF seen over a 10-year period. Each subject was assessed by a thorough medical history, dietary analysis and a full serum and urinary biochemical evaluation.

RESULTS

Although the WSF were significantly more overweight (P<0.001) and obese (P<0.001) than the BSF, neither group had values significantly different from those of their respective normal populations. There was no significant difference in serum levels of Ca, phosphorus, ionised Ca, calcitriol and alkaline phosphatase in BSF and WSF, but levels of parathyroid hormone tended to be (P<0.1) and calcitriol was significantly higher in BSF than WSF (P<0.03). The BSF urinary excretion levels tended to be more like that of the WSF, with the following pattern present; BN<BSF<WSF, except for citrate, where BSF< BN<WSF. No dietary or metabolic abnormality was found in 9% of BSF and 5% of WSF. Pure dietary lithogenic risk factors were present in 9% of BSF and 21% of WSF. The prevalence of metabolic risk factors was similar in the two groups but the distribution differed. Renal hypercalciuria, absorptive hypercalciuria and mild metabolic hyperoxaluria were 2.5-3 times more prevalent in the WSF.

CONCLUSION

Although the urine of BSF tends to be more like that of WSF, the lithogenic risk factors present differed and were less severe. The increase in urinary calcium excretion, coupled with a lower citrate excretion, may be the most important reason for stone formation in the black population. An increased protein intake may also play a role. In this small group of BSF there was no family history of urolithiasis, supporting the view that there may be a more prominent genetic influence in WSF.

Lithogenic risk factors in the urine of black and white subjects

OBJECTIVE

To identify biochemical and dietary factors which may play a role in the low incidence of stone formation in the black South African population.

SUBJECTS AND METHODS

The study included 31 semiurbanized black and 29 urbanized white subjects. The protocol and modern laboratory techniques used to assess recurrent stone formers were followed. Urinary sodium, potassium, creatinine, calcium, phosphate and urate levels were measured, and urinary citrate, oxalate and cystine assessed.

RESULTS

Black subjects ate a diet significantly higher in sodium (P < 0.04); there was no difference in serum levels but urinary sodium was significantly higher (P < 0.001) in black than in white subjects. Urinary potassium, calcium, citrate, phosphate and cystine were all significantly lower in black than in white subjects (P < 0.001 for the first four and P < 0.03 for cystine).

CONCLUSION

Certain intrinsic factors in South African black subjects may account for their lower frequency of stone formation than in white subjects. Of these, the very low urinary calcium, decreased urinary cystine and different interactions between sodium and calcium/cystine are probably important.

Paediatric urolithiasis in a remote Australian aboriginal community

A retrospective study of Community Health Service patient records revealed 10 cases of urolithiasis in Aboriginal children under 5 years of age in a remote central Australian Aboriginal community over a 4 year period, out of a total under-5 population estimate of 62. The highest attack rate was in the 0-2 age group, where nearly one in 10 children presented per year. All children had significant associated morbidity. Two children underwent pyelolithotomy. Aboriginal children in the remote arid zone study community suffer exceptionally high rates of urolithiasis. Inadequate diet, dehydration and recurrent infectious disease are factors in pathogenesis. Further study may elucidate aetiology, but the implications of these data for improving environmental conditions and health service delivery in Aboriginal communities are urgent.

Racial variation in gender frequency of calcium urolithiasis

Calcium oxalate stones are known to occur most frequently in the fifth and sixth decades of life and in a male-to-female ratio of approximately 2:1. However, previous data are from predominantly white populations or from multiracial populations that have included patients with infection stones. We reviewed a population of 444 consecutive patients (189 white, 123 black and 132 Hispanic) from 1 urban hospital treated by shock wave lithotripsy for symptomatic renal and ureteral calculi, and added a population of 260 patients treated at a university hospital in Japan. Patients with infection stones and those with uric acid or cystine stones were excluded. We found men to be more commonly afflicted in the white (62%) and Asian (64%) populations but noted a reversal of gender frequency in the black and Hispanic populations, of which women comprised 68% and 60% of the stone population, respectively. We conclude that calcium urolithiasis is more common in women than previously reported, and discuss the possible etiologies.

Epidemiologic features of urolithiasis among industrial employees. The Israeli CORDIS Study

We examined the prevalence of urolithiasis in 5574 men and women employees in 21 industrial plants in Israel who were screened for cardiovascular risk factors between 1985 and 1987 (the CORDIS Study). Among the data gathered were previous physician diagnosis of urolithiasis and ergonomic and demographic data. Urolithiasis was much more frequent in men than in women (age-adjusted prevalence of 4.5% in men and 1.2% in women, P < .0001). Older subjects had higher prevalence than young subjects. There were ethnic differences, and the highest prevalence was in subjects of European origin. Of the occupational factors, only industrial sector was related to prevalence of urolithiasis. Urolithiasis was more frequent among employees in wood industries than in other sectors (P < .05). We concluded that there is an effect of industrial sector on the prevalence of urolithiasis. To determine the cause and magnitude of the association of wood industries with increased prevalence of urolithiasis, ergonomic and chemical factors should be investigated.

Identification of a 7-basepair deletion in the adenine phosphoribosyltransferase gene as a cause of 2,8-dihydroxyadenine urolithiasis

We describe a family of Turkish origin with adenine phosphoribosyltransferase (APRT) deficiency and renal stone disease. The proband had 2,8-dihydroxyadenine urolithiasis but an older sister, who was also deficient in enzyme activity, is so far asymptomatic. The proband was homozygous for a 7-bp deletion in exon 3 of the APRT gene. One allele from each of the parents also contained this deletion. The patient and her father were homozygous for an intragenic TaqI RFLP (1.25-kb fragment) whereas the mother was heterozygous (1.25- and 1.91-kb fragments), indicating that the mutation was present on the allele carrying the 1.25 kb TaqI fragment. The deletion alters the reading frame downstream of codon 93 and would be expected to abolish enzyme activity.

[The immunogenetic associations in hereditary forms of urolithiasis]

A distribution rate of the leukocytic histocompatibility antigens of HLA loci, A, B, C and basic erythrocytic blood groups of the ABO system, rhesus, P, Duffy, Kell was investigated among people of Azerbaijani nationality suffering from the familial forms of urolithiasis. A practical value of the investigation is to directly use the obtained data during a prophylactic medical survey of population, specific therapeutic management and prognosis, detection of high risk groups and prenosologic diagnosis.

Pattern of urolithiasis in Benin City, Nigeria

A retrospective study was performed to determine the frequency and pattern of urinary stone disease in a black African population. Urolithiasis was found to be a rare condition in the black African occurring with a frequency of 6.3 per 100,000 hospital population, with a male:female ratio of 4:1. Urinary stasis and infection are associated or etiologically related factors in a significant number of patients. Idiopathic stone disease is uncommon (28% of patients). A recurrence rate of 10% is similar to that found in other areas of the world where the disease is more prevalent.

Urinary lithiasis in the black population: an epidemiological study and review of the literature

A retrospective review of 199 black patients with urinary calculi and review of the census figures of the index hospitals revealed that white patients had urinary calculi 3 to 4 times as often as black subjects. The black male-to-female ratio was 1 to 1.55 compared to a ratio for white patients of 2.3 to 1. Calculi in black male subjects occur at a younger age than in black or white female or white male patients. The most common organisms cultured in black patients with stones were Escherichia coli and Proteus mirabilis. In contrast to the white population the most common type of stone formed in black patients was struvite/carbonate apatite. Stones of this type accounted for a third of all stones in male and 44 per cent in female subjects. We conclude that nephrolithiasis is an uncommon but not rare disease in the American black population.

Trends in urolithiasis in various ethnic groups and by age, in Israel

A survey of upper urinary tract stone composition was carried out over 8 years (1974-1982) in 1147 patients, following a previous survey (1966-1974). Trends in the development of stone formation were found. The most obvious differences were fewer pure calcium oxalate (0.75 versus 5.50%) and uric acid stones (6.11 versus 13.30%) and more mixed stones than in our previous study. In most ethnic groups urinary stones were composed of calcium oxalate/calcium phosphate. A higher prevalence of stones in Israeli-born Jews was noted, in comparison with our previous survey. Age group analysis showed this increase to be limited to the 21-50-year-old group, in contradistinction to a clear decrease in stone formation in Israeli-born Arabs and Jews under the age of 20 years.