Study on the Prevalence and Incidence of Urolithiasis in Germany Comparing theyears 1979 vs. 2000

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1 European Urology European Urology 44 (23) Study on the Prevalence and Incidence of Urolithiasis in Germany Comparing theyears 1979 vs. 2 A. Hesse a,*, E. Brändle b, D. Wilbert c, K.-U. Köhrmann d, P. Alken d a Department of Urology, Division of Experimental Urology, University of Bonn, Sigmund-Freud-Str. 25, D-535 Bonn, Germany b Department of Urology, University of Ulm, Ulm, Germany c Department of Urology, University of Tübingen, Tübingen, Germany d Department of Urology, University Hospital Mannheim, Mannheim, Germany First published online 27 August 23 Abstract Objectives: In 1979, we conducted a representative study to determine the prevalence and incidence of urolithiasis in Germany. Significant progress in stone therapy and changes in nutritional and environmental factors since then consequently led to a second study in 21 under the same conditions as in Methods: A representative sample of 75 persons from all over Germany was questioned on the occurrence of urinary stones during their lifetimes (prevalence) and on acute urolithiasis in 2 (incidence). Additionally, data were collected on urinary stone therapy and metaphylaxis. The current data were then compared with those from Results: Prevalence has risen from 4 to 4.7 from 1979 to of the 5 64 year old males in 2 had already had urinary stones (females: 5.9). The current recurrence rate of urinary stones was estimated to be 42. In the year 2, the incidence of urolithiasis in Germany was found to be 1.47 (1979:.54). Over 4 of the stones were passed spontaneously. Conclusion: There has been a marked increase in the prevalence and incidence of urolithiasis in Germany within the last 22 years. This probably results from improvements in clinical-diagnostic procedures, changes in nutritional and environmental factors and a general apathy towards metabolic clarification and metaphylaxis. # 23 Elsevier B.V. All rights reserved. Keywords: Epidemiological study; Urolithiasis; Prevalence; Incidence 1. Introduction Epidemiological data on the occurrence of urolithiasis ranges between 2 and 2 [1 3]. Precise data on the epidemiology of a disease or disorder can only be determined if geographical position, race, and sex, climate, nutrition and other environmental factors are also taken in consideration. The parameter occurrence is determined by two factors: (1) the incidence, i.e. the number of new disease cases per population measured over a given time interval and (2) the prevalence, i.e. the portion of people in a population who found to be with disease at a certain point in time. A representative survey of the incidence and prevalence * Corresponding author. Tel.þ ; Fax:þ address: hesse@uni-bonn.de (A. Hesse). of a disease is only possible using randomly selected samples of the general population questioned in faceto-face interviews or by telephone. Comparisons between different regions or countries are only permissible when the survey criteria are comparable. One explanation for the large fluctuations in the urolithiasis data gathered from different countries is that these were based only on selected groups, such as males over the of 4, urban or rural populations. Only few reports on the epidemiology of urolithiasis are available based on nation-wide surveys [4 7]. The overall structure of the population has not always been taken into account in these studies [4,8]. These studies produced prevalence data ranging from 4 [6] to 14.8 [7]. Chronological studies have shown that urolithiasis is on the increase. Within years ( ) the /$ see front matter # 23 Elsevier B.V. All rights reserved. doi:.16/s (3)415-9

2 7 A. Hesse et al. / European Urology 44 (23) prevalence rose from 4 to 5.4 in Japan [5]. In 1979, we conducted a representative study for the Federal Republic of Germany, which showed the prevalence of urolithiasis to be 4. and the incidence.54 [6].Using the same survey structure, this survey was repeated in 21, so that reliable data on the development of urolithiasis would be obtained over the 22-year period. 2. Materials and methods In co-operation with INFAS (Institute for Applied Social Science) two representative, epidemiological surveys on urolithiasis were conducted (1979 and 21). In each case the questions relating to urolithiasis were posed within the framework of a multi-topic survey. In 1979, the survey was conducted face-to-face on a representative sample of,13 people. In 21, 75 people were included in the survey and were asked by telephone interviews. They were selected by following different criteria in the telephone directory: Selection by area: Criteria were the size of a location and its population density in the various federal states in Germany. Selection by household: Selection was based on the current telephone CD-ROMs. Households not appearing in the directories were selected using an extended Random Last Digit (RED) system developed by INFAS. This system ensured that both households in the directories and those not included in them would be equally selected. Selection by person: Children under 14 years of were not included in the survey. The random sampling within a household was based on the last-birthday system, under which the member was questioned who had last had a birthday. The telephone interviews were conducted using a special computer-assisted programme system. The process data and the appointments made were administered centrally to ensure automatic updating of the survey. The survey was conducted in three cycles of 25 persons each, and the interim results of each one were documented. The main resulting statements on prevalence and incidence were confirmed in the individual cycles, so that the final result led to highly valid data. The conduct of these epidemiological studies from the years 1979 and 21 has led to comparable representative results. The following questions were posed: 1. There is a disorder called urolithiasis. This embraces kidney stones, bladder stones and stones lodged in the renal duct. Gallstones are excluded. Has any doctor found you to be suffering from this disorder in the year 2 or before? Further questions followed, but only where urolithiasis had been diagnosed: 2. How often had you had this disorder prior to the year 2? 3. Did you have urinary stones for the first time in 2, or had you had them before? 4. How old were you when your doctor first diagnosed urinary stones? 5. How was your urolithiasis treated? using shock waves using an endoscopic process, i.e. cytoscopic inspection of the bladder or ureter, or percutaneously through the skin surgically spontaneous discharge of the stones no treatment 6. What are you yourself doing to prevent new stones? I drink a lot I have reorganised my diet I take regular medication Questions 1 4 were posed identically in 1979 and 21. Questions 5 and 6 were only used in Results 3.1. Prevalence The prevalence of urolithiasis has increased from 4. to 4.7 within 22 years (Table 1). In the year 21, 5.5 of males and 4. of females stated that they had already suffered from urinary stones once or more. The mean ratio between male and female was 1.4:1. For patients over the of 5 the prevalence was 9.7 for males and 5.9 for females (Fig. 1). Analysis of the when urolithiasis occurred for the first time amongst all stone patients interviewed in 21 revealed a marked increase in both females and Table 1 Prevalence of urolithiasis in Germany, comparison between the years 21 and Interviewed persons (n ¼,13) Interviewed persons (n ¼ 753) Males (n ¼ 462) Males (n ¼ 3573) Females (n ¼ 55) Females (n ¼ 393) Stone patients (n ¼ 48) Stone patients (n ¼ 355) Males (n ¼ 183) 3.96 Males (n ¼ 197) 5.51 Females (n ¼ 225) 4.8 Females (n ¼ 158) Prevalence of Urinary Stones 21 Age-distribution and sex female (n=158) male (n=197) >= 65 Fig. 1. Prevalence 21: distribution and sex of patients with urolithiasis.

3 A. Hesse et al. / European Urology 44 (23) female male 5.6 Age at the first stone episode n= >= 65 Fig. 2. Age at the first stone episode for all stone-patients in the survey Table 3 Incidence of urolithiasis in Germany, comparison between the years 1979 and First manifestation Male ().8.43 Female ().4.29 Total () Recurrency Male () Female () Total () Summary () Prevalence of Urinary Stones 21 vs Age-distribution 1979 (n=48) 21 (n=355) 3,8 3,8 5,4 7,7 6,8 9,5 Table 4 Age- and gender-dependence of the incidence of urolithiasis in the year 2 Age Male (n ¼ 63) Female (n ¼ 48) > ,1,7 1,4 1, >= 65 Fig. 3. Age distribution of stone-patients in the years 21 and males at the of 25 onwards. Particularly in the case of males, this trend was continuous (Fig. 2). The comparison of the distributions of stone patients in the years 21 and 1979 clearly reveals that the increase in prevalence is primarily attributable to the higher groups (>5) (Fig. 3). Over 4 of respondents stated that they had suffered from urolithiasis a number of times (Table 2). Over had had five or more stone episodes Incidence 1.47 of respondents had had urinary calculi in the year 2 (Table 3). 5 of these were first occurrences, and 5 were recurrences. The incidence was Table 2 Frequency of urolithiasis (), n ¼ 355 Once 58.3 Twice 17.7 Three times 9.6 Four times 2.3 Five times or more.1 Don t know/reply refused 2. always higher with the males than with the females (Table 3). In comparison to 1979 the incidence dramatically increased (1.47 vs..54). No measurable cases of lithiasis occurred under the of 25 in 2. In the case of females, an earlier marked increase was recorded from the of 35, and with the males, there was a sharp increase from the of 5 onwards (Table 4). Two sets of interviews (n ¼ 5) were designed to identify the type of treatment the patients received for stone disease in the period The types of treatment administered are summarised in Table of respondents stated that their stone was removed by surgery. The high percent of surgical operations is however questionable. Daily experience and data reported in the literature indicate that Table 5 Therapy for stone removal a Nature of the treatment ESWL 22 URS/PNL 15 Surgery 17.5 Spontaneous discharge 28 None 13.5 Refused 7.5 Not known 4.5 a Replies from stone-formers (n ¼ 135) who had stone episodes between the years 1996 and 2 (multiple reports permitted).

4 712 A. Hesse et al. / European Urology 44 (23) Table 6 Precautions against recurrence High fluid intake 89 Reorganisation of diet 37 Regular medication 9 Refused answer 1 Not known 7 frequency of surgical procedures for stone removal is less than 1 in Germany. The administration of an anaesthetic was perhaps often assumed to be an operation. Moreover, it may be assumed that no treatment implies a spontaneous discharges of the stone, i.e. over 4 of the stones were passed spontaneously. This discrepancy indicates that no matter how sophisticated the question technique may be, no precise replies can be expected from the medical laity. Amongst the prophylactic precautions adopted to prevent recurrences, 89 of the patients gave a high fluid intake (drinking) and 37 a change in diet. Only 9 took any regular medication as stone prophylaxis (Table 6). In the year 2, the largest number (49) of stone recurrences was found in the 5 64 year group. 4. Discussion In former times, most epidemiological studies of urolithiasis were based on hospital statistics, general practice surveys or selected group surveys [9,]. These produced many interesting details regarding this multifactorial disease, but, for a number of different epidemiological reasons, they are inadequate for determining the true prevalence and incidence in a population. Furthermore, a comparison between different countries, and a chronological assessment is not possible using data from this specific group of patients. In recent years, surveys and analyses conducted under health care programmes generated epidemiological data for urolithiasis in specific regions [5,7,8,11,12]. These produced prevalence data ranging from 3.5 to These results underscore the significance of urolithiasis for public health policy in the different countries, but they also reflect the problems attending to epidemiological studies. In a nation-wide study, the following selection criteria must be taken into account: structure, gender, place of residence, occupation, etc. The samples should be representative of the entire population. In large states, variations in climatic zone, differences in eating habits, and also different degrees of industrialisation, create additional problems for epidemiological studies. Hence if reliable data are to be collected, validated instruments must be used. For our first survey on the prevalence and incidence of urolithiasis in 1979 we worked in conjunction with the renowned Institute for Applied Social Sciences (INFAS), and we were also able to conduct the current study in 21 together with this institute. In this way we retained its representative character for Germany, and maintained almost total reliability of comparability. This is indispensable if chronological conclusions are required. The survey was conduct in three cycles of 2,5 persons each, and the interim results of each one were documented. The main resulting statements on prevalence and incidence were confirmed in the individual cycles, so that the final result led to highly valid data. The rise in the prevalence of urolithiasis from 4. to 4.7 (1979 vs. 21) is considerable, and INFAS has even projected to reach 5. Surprising, but equally valid, is the high incidence of 1.47 in the year 2. In comparison with 1979 a rise of over 17 was determined (Table 3). This rise is attributable to both new and recurrent stone formers. Our study could not be based solely on symptomatic stones, since patients with asymptomatic stones had also been registered as stone formers. Modern imcreation processes have led to a marked improvement in early diagnosis. However, there is every chance that, due to undiagnosed stones, the true prevalence and incidence lie quite a bit higher than was found in our study. We assume that the progress made in diagnostic procedures sonography, spiral-ct, etc. in the past 2 years has radically improved the detection of urinary calculi, so that stones are now be diagnosed earlier and often at an symptomatic st. Changes in diet, however, have also contributed to this rise in the prevalence and incidence of urolithiasis. Within a period of years ( ), Yoshida and Okada (199) detected a rise in the prevalence of urolithiasis from 4 to 5.4, and attributed this to increasing industrialisation and westernisation of life-style in Japan [5]. After an interval of 12 years ( ), Trinchieri et al. (2) re-examined every adult in a vill near Milan. The prevalence of urolithiasis in males had risen from 6.8 to.1, and in females from 4.9 to 5.8 (1986 vs. 1998). These authors also attribute the rise in renal stones to environmental factors, such as dietary habits and lifestyle [13]. The high incidence of first occurrences in our study amongst the 25 5 year olds (Fig. 2), i.e. those at the most active st of their careers, also supports the proposition that life-style and eating and drinking

5 A. Hesse et al. / European Urology 44 (23) habits might be important causative factors. We were only able to detect any higher degree of prevalence in 1979 vs. 21 from the of 5 onwards (Fig. 3). However, increasing numbers of younger women are now suffering from urinary stones, a fact which becomes clear both from the incidence (Table 4) and from the initial stone episode. Stamatelou et al. [14] were also able to detect this latter fact. Robertson [15] was the first to detect a link between rising protein consumption and stone formation. In our previous studies, we have also examined the influence of diet on the risk of urinary stone formation [16,17], and confirmed the increasing hazard from protein-rich diets producing strong acidification of the urine. The rise in the recurrence rate, as expressed in the incidence of urolithiasis in the year 2, is also attributable to a growing apathy towards metabolic work-up, and inadequate metaphylaxis. The necessary improvement in urinary dilution was sustained by nearly 9 of the stone patients in our study, but only 9 took any regular medication to prevent stone formation. Lithotripsic methods have attained a high degree of perfection, creating the impression of a perfect therapy for stone removal. A stone in a kidney, a ureter or the bladder, however, is only the symptom of a disorder. After removal of the stone, continual further check-ups and adequate prophylactic precautions against any recurrence are still required. The results of our latest epidemiological studies on the chronological development of urolithiasis underscore the necessity for improved care after removal of the stone. Acknowledgements This study was supported by grants of the German Society of Shock Wave Lithotripsy, Dornier Medizintechnik (Wessling/Germany), Philips Medizin Systeme (Hamburg/Germany) and STORZ Medical (Kreuzlingen/Germany). References [1] Pak CYC. Kidney stone. Lancet 1998;351: [2] Hesse A, Siener R. Current aspects of epidemiology and nutrition in urinary stones. World J Urol 1997;15: [3] Trinchieri A. Epidemiology of urolithiasis. Arch It Urol 1996;LXVIII: [4] Ljunghall S, Hedstrand H. Incidence of upper urinary tract stones. Min Electr Metab 1987;13:22 7. [5] Yoshida O, Okada Y. Epidemiology of urolithiasis in Japan: a chronological and geographical study. Urol Int 199;45:4 11. [6] Vahlensieck EW, Bach D, Hesse A. Incidence, prevalence and mortality of urolithiasis in the German Federal Republic. Urol Res 1982;: [7] Akinci M, Esen T, Tellaloglu S. Urinary stone disease in Turkey: an updated epidemiological study. Eur Urol 1991;2:2 3. [8] Curhan GY, Rimm EB, Willett WC, Stampfer MJ. Regional variation in nephrolithiasis incidence and prevalence among united states males. J Urol 1994;151: [9] Boyce WH, Garvey FK. Incidence of urinary calculi among patients in general hospitals, 1948 to JAMA 1956;161: [] Scott R, Freeland R, Mowat W, Gardiner M, Hawthorne V, Marshall RM, et al. The prevalence of calcified upper urinary tract stones in a random population the Cumbernauld health survey. Brit J Urol 1977; 49: [11] Borghi L, Ferretti PP, Elia GF, Amato F, Melloni E, Trapassi MR, et al. Epidemiological study of urinary tract stones in a Northern Italian City. Br J Urol 199;65: [12] Thun MJ, Schober S. Urolithiasis in Tennesee: an occupational window into a regional problem. Am J Public Health 1991;81: [13] Trinchieri A, Coppi F, Montanari E, Del Nero A, Zanetti G, Pisani E. Increase in the prevalence of symptomatic upper urinary tract stones during the last ten years. Eur Urol 2;37:23 5. [14] Stamatelou KK, Fancis ME, Jones CA, Nyberg Jr MN, Curhan GC. Time trends in reported prevalence of kidney stones in the United States: Kidney Int 23;63: [15] Robertson WG, Peacock M, Hodgkinson A. The effect of dietary changes on the incidence of urinary tract stones in the UK between 1958 and J Chron Dis 1979;32: [16] Hesse A, Siener R, Heynck H, Jahnen A. The influence of dietary factors on the risk of urinary stone formation. Scanning Microscopy 1993;7: [17] Siener R, Hesse A. The effect of different diets on urinary composition and the risk of calcium oxalate stone formation in healthy subjects. Eur Urol 22;42: