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An epidemiological study of 422 stone-formers who visited our hospital from 1997 to 2001 was conducted. The mean annual prevalence and incidence of both upper and lower urinary tract stones were higher than what was found in a nationwide urolithiasis survey carried out in Japan in 1995. The incidence of upper and lower urinary tract stones was 90.8% and 9.2%, respectively. The frequency of lower urinary tract stones was higher than that found in the previously mentioned nationwide study. The male-to-female ratio of upper and lower urinary tract stones was 1.68:1 and 2.25:1, respectively. The frequency in females was higher in this study than that found in the nationwide survey. The peak age for incidence of upper urinary tract stones is 50s in males and females. In the treatment of upper urinary tract stones, ureteroscopic lithotripsy was carried out more often than shock wave lithotripsy (SWL), because our hospital had no SWL device. Many endoscopic lithotripsy procedures were performed to treat stones located in the lower urinary tract. Of the upper urinary tract stones 83.7% were composed of calcium, the incidence of uric acid stones was high (6.6%), whereas the incidence of infectious stones was low (1.9%). For lower urinary tract stones, the frequency of infectious stones was high (52.6%). In the present study, the epidemiological features were as follows: high annual prevalence and incidence, high frequency of lower urinary tract stones, high frequency in females, many endoscopic treatment procedures and high frequency of uric acid stones in the upper urinary tract.

Surgical treatment for upper urinary stones has dramatically changed since extracorporeal shock wave lithotripsy (ESWL) was introduced in 1985 in Japan. Since then, the number of ESWL apparatus is increasing year by year, and there were about 800 ESWL apparatus available in Japan in 2001. On the other hand, the number of patients with upper urinary stones are also increasing in Japan, and the age-adjusted annual incidence of first-episode upper urinary tract stones in 1995 was estimated at 68.9 per 100,000 (100.1 in men and 55.4 in women), a steady increase from 54.2 in 1965. Under these circumstances, it would be very important to treat stone patients surgically even from an economical point of view, because the cost of ESWL is very expensive and more than 90% of the patients with urolithiasis are now treated by ESWL. In this paper, the medical economics of urolithiasis in Japan is discussed especially in the surgical treatment.

Toyooka Hospital is a central hospital in Tajima, a rural area in the northern part of Hyogo Prefecture. Because we possess the sole lithotripter in this area, almost all urolithiasis patients requiring treatment have been referred to our department. Based on the number of urolithiasis patients treated in our institution, we estimated the annual prevalence and incidence of upper urinary tract stones in the Tajima area. The mean annual prevalence of urolithiasis and incidence during the 1991-1993 period were 141 and 93 per 100,000, respectively. The male to female ratio was 2.0 to 1 in prevalence and 2.2 to 1.0 in incidence. Prevalence was highest in the sixties (245) and fifties (235), followed by the forties (205), seventies (162) and thirties (160). The incidence was highest in the fifties (169), followed by the forties (147), sixties (145) and thirties (118). In consideration of sex, the incidence was highest in males in the fifties and the forties. Of the patients with upper urinary calculi, 23.1% were treated by extracorporeal shock wave lithotripsy, while in 23.8% stones passed spontaneously and 50.9% were followed up without treatment. On stone analysis, calcium oxalate and/or calcium phosphate was present in 75.6%, uric acid in 16.4%, struvite and/or carbonate apatite in 5.6% and cystine in 1.4%. In summary, the prevalence and incidence of upper urinary tract calculi in the Tajima area were considerably higher than those in the nationwide survey on urolithiasis in Japan conducted in 1985.

Statistical observations of the inpatient operations at our department during the 27-year period from 1970 to 1996 revealed the following: A total of 9,287 operations were performed, comprising 7,488 males and 1,799 females. Operations for urolithiasis numbered 3,646 (39.3%) which was the most frequent, followed by operations for urological malignancies, 2,038 (21.9%) and for prostatic hyperplasia, 1,596 (17.2%). In the last decade, the number of operations for malignancies, prostatic hyperplasia, and especially for urolithiasis has increased. However the number of operations on pediatric cases has shown a marked decrease. Thanks to the development of new diagnostic and therapeutic medical modalities, including ultrasound, computed tomographic scans, endoscope and extracorporeal shockwave lithotripsy, the frequency of early cancer has thus increased, and the surgical procedure of choice has dramatically shifted to minimally invasive surgery.

During the 11-year period from September 1984 through August 1995, extracorporeal shock wave lithotripsy (ESWL) was performed on 5,558 patients using a Dornier HM3 apparatus. A recurrence questionnaire was sent out to 2,379 of those who had had complete elimination of the calculi and for whom at least 3 years had passed since the ESWL. The last day of follow-up was defined as follows: the day of completion of the questionnaire in the recurrence-free group (n = 787), the day when recurrence of calculi was diagnosed in the recurrence group (n = 415) and the day of the last visit to the outpatient clinic in the miscellaneous group (n = 1,133). The cumulative recurrence rates were calculated by the Kaplan-Meier equation. The resultant data were analyzed for statistically significant differences by the log rank test and the generalized Wilcoxon test. Ap value of < or = 0.05 was considered to indicate significance. The recurrence rate was examined for differences in relation to the following risk factors: the patients' age and sex, the stone location, size and number, the presence or absence of past history of lithiasis, the composition of the stone (s), and the presence or absence of urinary tract complications. The cumulative recurrence rates for the total cases were 2.0% at one year, 13.1% at 3 years, 23.9% at 5 years, 30.7% at 7 years and 40.7% at 10 years. Significantly higher recurrence rates were found for patients under 60 years of age, those with multiple stones and those with a past history of disease.

We report the clinical statistics of new outpatients for five years since 1989 at our hospital. The average total number of new outpatients in a year was 8309.8 (8122-8691) and new outpatients tended to show little change. The male to female ratio was 1.57:1, and 24.3% of the outpatients were referred to us by others sources. The representative operations on outpatients were circumcision, vasectomy, resection of condyloma and resection of caruncle. A statistical study was made on new outpatients according to the international classification of disease. There were 140.6 (1.97%) malignant urogenital tumors per year. Sexually transmitted diseases showed a tendency to increase for the last five years. In males the major disease was upper urinary tract stone (21-24%), prostatistis (21-24%) and benign prostatic hypertrophy (17-20%) and in females they were cystitis (58-61%), upper urinary tract stone (15-17%) and pyelonephritis (3-4%). We conclude that our hospital plays a major role as a private urological hospital.

Between August 1987 and December 1990, 546 patients were admitted to the department of Urology at the Poh Ai Hospital of I-Lan, Taiwan, R.O.C. for the treatment of urinary stones. These urinary stone cases accounted for 50 to 60% of all urology patients admitted. The incidence of urolithiasis in I-Lan was estimated at 147/100,000 population in 1990. There were 402 male patients and 144 female patients, The male to female ratio was 2.8: 1. There were 450 upper urinary tract stones (kidney, ureter) in 314 males and 136 females, and 79 lower urinary tract stones (bladder, urethra) in 72 males and 7 females. The ratio of upper to lower urinary tract stones was 6:1. Endourological treatments such as percutaneous nephrolithotripsy and transurethral ureterolithotripsy have increased rapidly in recent years. A summary of the present analysis for composition of 365 stones follows. The most frequent type was calcium-containing stone (92.3%), followed by infection stone (4.7%), then uric acid (UA) stone (3.0%). There were no UA stones found in the female patients. According to urinalysis criteria of more than 10 WBC/HPF (x 400), pyuria was found in 67 cases of 334 metabolic stones (20.1%), and 11 cases of 17 infection stones (67.7%). There were neither pediatric case of stone formation nor cystine stones.

To determine the current status of urolithiasis in 1988, in comparison with that in 1985, we analyzed the 1937 patients of urolithiasis at 17 departments of urology in Mie Prefecture and 2 departments of urology in Wakayama Prefecture. The ratio of male to female patients was 2.6 to 1.0. Geographically, the number of urolithiasis patients was most frequently distributed in Matsusaka City. The frequency of urolithiasis in the urban area was almost the same as that in the rural area. Most of the stones (96.3%) were in the upper urinary tract. The frequency of lower urinary tract calculi tended to be high in southern Mie Prefecture. The ratio of the upper urinary tract calculi to the lower urinary tract calculi in the urban area was higher than in the rural area. The age distribution in males was in the forties, while that in females was in the fifties. The average age was 46.4 years old. The surgical treatment was performed in 671 patients (34.6%) and the extracorporeal shock wave lithotripsy (ESWL) was the most frequent mode of treatment (85.0%), followed by cysto-lithotripsy (4.2%) and percutaneous nephro-uretero-lithotripsy (2.4%). The most frequent component of the urinary tract calculi was calcium oxalate and/or calcium phosphate (81.7%). The stone patient increased in the number during the summer season (July, August and September). In conclusion, in 1988 when the ESWL treatment started in Mie Prefecture, the epidemiologic features of urolithiasis was characterized as follows: the number of patients increased and the broad application of the ESWL treatment resulted in the decreased number of patients with spontaneous discharge and the increased number of patients with recurrent stones and with bilateral or multiple complex stones.

The purpose of this study was to determine the incidence of the urological diseases of the kidney. Among 4,094 persons (3,146 men and 948 women) studied, 86 cases of renal cyst, 7 cases of urolithiasis, 3 cases of cystic kidney, and one case of renal cell carcinoma were discovered. The rate of renal cyst was two times higher in men than in women. One sixth of renal cyst patients showed microscopic hematuria. Renal cysts tended to progress in number and size with age. The size of the renal cyst did not correlate with the appearance rate of microscopic hematuria.

To determine the present status of urolithiasis in Mie Prefecture, we analyzed the 1,314 patients of urolithiasis at 17 Departments of Urology and 2 Departments of Medicine in 1985. The ratio of male patients to female patients was 2.6 to 1. The most frequent incidence of urolithiasis was observed in Iinan county. The incidence of urolithiasis in the urban area was the same as that in the country. Most of the stones (96.9%) were in the upper urinary tract. The incidence of lower urinary tract calculi tended to be high in southern Mie Prefecture. The ratio of upper urinary tract calculi to lower urinary tract calculi in the urban area was the same as that in the country. The peak incidence in males was in the forties, while that in females was in the fifties. The average age was 44.5 years old. Ureterolithotomy was the most frequent (37.5%) surgical therapy, percutaneous nephrolithotomy and shock wave lithotomy done in 8.0% and 6.3%, respectively. The most frequent component of the urinary tract calculi was calcium oxalate and/or calcium phosphate (84.0%). The incidence increased in summer (April through September).

During the 13 years from July, 1971 to August, 1984, 1896 patients were diagnosed as urolithiasis at our University Hospital. These cases were retrospectively analyzed. The male to female ratio was 2.4 to 1. The peak age incidence of urinary calculi occurred in the third decade. The ratio of upper urinary tract stones to lower urinary tract stones was 18 to 1. As to the laterality of the upper urinary tract stones, the ratio of left to right was 1.3 to 1. Analysis of the stone components revealed that the frequency ob calcium oxalate mixed with calcium phosphate and pure calcium oxalate was 80 percent and struvite, uric acid & cystinine were 14.1%, 2.6%, 1.6% respectively.

A statistical study was performed on new outpatients, the total number of which was 7,786 (male: 4,953, female: 2,833) in 1985. The male to female ratio was 1.75:1. They had urogenital diseases definitely diagnosed (6,786), tentatively diagnosed (600), normal (260), and diseases other than urogenital (140), and 36.2% of them had been referred to us by other sources. On these outpatients 206 operations had been performed circumcision, resection of condyloma and vasectomy were representative. The peak of the age distribution was in the thirties for males and in the twenties for females. For the first time in Japan, we treated renal and upper ureteral stones using extracorporeal shock wave lithotripsy (ESWL) on September 1, 1984. The results of ESWL at out hospital have been satisfactory. A statistical study was made on new outpatients according to the international disease classification. There were 152 malignant (urogenital) tumors (2.1%). The major diseases of the new outpatients were cystitis (acute or chronic: 20.6%), upper urinary tract stones (19.4%), prostatitis (13.5%), benign prostatic hypertrophy (10.7%). In males the major diseases were prostatitis, upper urinary tract stones, benign prostatic hypertrophy, balanoposthitis, and phimosis, and in females they were cystitis, upper urinary tract stone, pyelonephritis, and renoptosis. We conclude that our hospital plays a major role as a private urological hospital.

Questionnaires about stone recurrence after treatment with percutaneous nephrolithotripsy (PNL) or extracorporeal shock wave lithotripsy (ESWL) were sent to 11 hospitals in the central section of Japan. We received 255 replies on PNL cases and 157 replies on ESWL cases. These patients were evaluated for the recurrence of renal stones and the enlargement of residual stone fragments. The effect of the medical management for the prevention of recurrent stone disease on postoperative recurrence rate was also evaluated. The average follow-up period of patients treated with PNL was 21.6 months, and 18.5 months for patients treated with ESWL. In patients who underwent PNL, 25 of 162 patients (15.4%) who were treated completely without any residual stones have suffered from new stones. The residual stone or fragments enlarged in 14 of the 93 patients (15.1%) who had residual stones or fragments after the treatment. The recurrence rate was significantly higher for the recurrent stone former than the single stone former. The recurrence rate for the patients who had multiple stones, staghorn calculi and metabolic disorders such as hypercalciuria also had a high incidence. Patients who received medical treatment for the prevention of stone recurrence had a lower recurrence rate than the group not treated. Especially among the patients with hypercalciuria, the recurrence rate of stone disease in the treatment group was significantly lower than that in the group not treated.(ABSTRACT TRUNCATED AT 250 WORDS)

In this paper, urolithiasis is reviewed from the standpoint of analytical epidemiology, which examines a statistical association between a given disease and a hypothesized factor with an aim of inferring its causality. Factors incriminated epidemiologically for stone formation include age, sex, occupation, social class (level of affluence), season of the year and climate, dietary and fluid intake and genetic prodisposition. Since some of these factors are interlinked, they are broadly classified into five categories and epidemiologically looked over here. Genetic predisposition is essentially endorsed by the more frequent episodes of stone formation in the family members of stone formers, as compared to non-stone formers. Nevertheless, some environmental factors (likely to be dietary habits) shared by family members are believed to be relatively more important than genetic predisposition. A hot, sunny climate may influence stone formation through inducing dehydration with increased perspiration and increased solute concentration with decreased urine volume, coupled with inadequate liquid intake, and possibly through the greater exposure to ultraviolet radiation which eventually results in an increased vitamin D production, conceivably correlated with seasonal variation in calcium and oxalate excretion to the urine. Urinary tract infections are importantly involved in the formation of magnesium ammonium phosphate stones in particular. The association with regional water hardness is still in controversy. Excessive intake of coffee, tea and alcoholic beverages seemingly increase the risk of renal calculi, though not consistently confirmed. Many dietary elements have been suggested by numerous clinical and experimental investigations, but a few elements are substantiated by analytical epidemiological investigations. An increased ingestion of animal protein and sugar and a decreased ingestion of dietary fiber and green-yellow vegetables are linked with the higher probability of stone formation in the industrialized countries. No trace elements in foodstuffs and liquids have been epidemiologically associated. The dietary guidelines for avoiding stone formation and/or recurrence are summarized in this paper, including other daily-life recommendations.

A clinical statistic survey was carried out on the patients, diseases and operations experienced at our urological clinic in 1984. The total number of inpatients was 1314, the male to female ratio being 2.97:1. The major diseases of the inpatients were urolithiasis (452 cases, 34.4%), and BPH (297 cases, 22.6%). Among the operations, TUR-P 34.1%, ESWL 33.0%, TUR-BT 6.9% were predominant.

In this paper, urolithiasis is remarked from the standpoint of descriptive epidemiology, which examines the frequency distribution of a given disease in a population in terms of time, place and personal characteristics with an aim of identifying risk factors or some clues to the etiology. Some descriptive epidemiological features of urolithiasis are summarized. Prevalence rate is around 4% (4-15% in males and 4-8% in females), and incidence rate varies from area to area: 53.2 per 100,000 population in 1975 in Japan, 364 in 1976 in Malaysia, and 540 in 1979 in West Germany. Prevalence and/or incidence rates have, in general, increased in the developed countries since World War II and in the developing countries as well, where upward trends are quite analogous to the trends observed in the nineteenth century in Europe. Recurrence rate, which is much higher in males than in females, ranges from 31% to 75%, depending on the follow-up periods. In the industrialized countries, upper urinary (renal and ureteral) stones account for more than 90% of total stones, which are ordinarily calcium complexes in composition. More common in the developing countries are lower urinary (bladder and urethral) stones, frequently composed of magnesium ammonium phosphate, which indicates a close association with urinary tract infections. Variations in frequency are evident by season and by region within a country. Age and sex differentials in urinary stone formers are substantial: more common in males 30-40 years old in the industrialized countries and in children under 10 years old in the developing countries. Racial differentials are also noted; blacks appear to suffer less frequently than whites. Stone formers experience more frequent episodes of stone formation in their family members, particularly father and brothers, than non-stone formers. These findings on racial differentials and family preponderance suggest the possible relevance of genetic factors in stone formation. Stone formers are more likely to be occupationally sedentary and socially affluent. This observation and differentials by age and sex suggest the probable relevance of lifestyle and environmental factors in stone formation. Epidemiological factors incriminated for stone formation will be discussed in a separate paper.

In our laboratories, more than 1,500 urinary calculi have been analyzed by infrared spectroscopy. These data were statistically analyzed by microcomputer. The most frequent type was calcium oxalate combined with calcium phosphate, followed by pure calcium oxalate and magnesium ammonium phosphate combined with calcium phosphate. In particular, the composition of magnesium ammonium phosphate combined with calcium phosphate increased as compared with that four years earlier. Four years ago, we spent one month to statistically analyze 300 urinary calculi. But in this study, only sixteen days was required to analyze 1,500 urinary calculi by using a microcomputer.