Guarantor: MAJ Karen Baker, MC USA Contributors: MAJ Karen Baker, MC USA*; COL Raymond A. Costabile, MC USA (Ret.) Methods.

Transcription

1 MILITARY MEDICINE, 172, 5:498, 2007 Demographics, Stone Characteristic, and Treatment of Urinary Calculi at the 47th Combat Support Hospital during the First 6 Months of Operation Iraqi Freedom Guarantor: MAJ Karen Baker, MC USA Contributors: MAJ Karen Baker, MC USA*; COL Raymond A. Costabile, MC USA (Ret.) There are few publications describing urolithiasis in deployed military personnel. Renal colic was the most common urologic indication for air evacuation from the 47th Combat Support Hospital during the first 6 months of Operation Iraqi Freedom and we describe our observations and experience herein. Institutional review board approval was obtained to create a database of patients presenting to the 47th Combat Support Hospital with urolithiasis. Patient demographics, stone characteristic, imaging modality, urinalysis results, treatment course, and outcomes were evaluated for 182 patients. Sixty percent of patients qualified for conservative treatment and spontaneous stone passage was documented in 28%. We conclude that conservative therapy is safe and appropriate initial treatment for the majority of deployed personnel with urinary calculi, however, many patients were lost to follow-up. No patient treated conservatively required admission for sepsis, azotemia, or other serious stone-related complication. Introduction lthough the impact of urinary calculi on the military mission A is difficult to quantify, renal colic was a frequent reason for referral to the 47th Combat Support Hospital (CSH), Camp Wolf, Kuwait, and the most common urologic indication for air evacuation out of theater. Yet, despite the apparent prevalence of stone disease in military personnel deployed to desert environments, there are few publications addressing basic information such as patient demographics, stone characteristics, necessity for air evacuation, and the success of treatment in the field. The influx of military and civilian Department of Defense personnel into southwestern Asia in support of Operation Enduring Freedom and Operation Iraqi Freedom (OIF) provided a unique opportunity to observe stone disease in the deployed population. Southwestern Asia is a high risk area for urolithiasis with a reported incidence of urinary calculi up to five times higher than other regions of the world. 1 4 During the 6-month period of this study, the 47th CSH was the largest tertiary referral hospital for the military theater and was the main evacuation route for southwestern Asia. As a result, the majority of renal colic requiring definitive diagnosis, subspecialty care, hospitalization, or evacuation was cared for at the 47th CSH. The objectives of this study were to evaluate patient and stone demographics, determine the time interval until formation of a *Madigan Army Medical Center, MCHJ-SU (Urology), Tacoma, WA Jay Y. Gillenwater Professor of Urology, Urology Department, University of Virginia Health System, Charlottesville, VA Presented at the XXXV International Congress on Military Medicine, September 12 17, 2004, Washington, D.C. and at the 51st Kimbrough Urologic Seminar, January 11 16, 2005, San Antonio, TX. This manuscript was received for review in May The revised manuscript was accepted for publication in August symptomatic stone, and evaluate treatment outcomes and indications for air evacuation at a single, level III military treatment facility (MTF) deployed in support of OIF. Herein, we summarize our experience diagnosing and treating urolithiasis in the combat and early posthostilities operations during the first 6 months of OIF. Our goals are to provide information to aid in the diagnosis and treatment of renal colic in the deployed environment, improve the planning of medical support operations, and provide insight into the timing of stone formation. Methods Database Construction and Demographics Institutional review board approval was obtained to construct a database of all patients who presented to the 47th CSH from March through July 2003 for the diagnosis, treatment, or further air evacuation of symptomatic urinary calculi. The database included the patient demographics, stone characteristics, imaging modality, date of arrival into theater, date of the onset of renal colic, urinalysis results, treatment outcomes, and indication for air evacuation. Imaging Modality, Stone Characteristics, Time Interval All patients included in the database were evaluated by a urologist at the 47th CSH and had urinary calculi or evidence of a recently passed calculi (e.g., unilateral hydroureter or periureteral stranding) documented by standard radiographic criteria. Imaging studies were not repeated if the patient arrived with images adequate to confirm the diagnosis or if the patient was referred from an outlying facility by a urologist who included in the medical summary a description of the radiographic findings adequate to confirm the diagnosis and characterize the stone. If more than one modality was performed, only the diagnostic imaging modality was recorded in the database. Patient demographics and stone characteristics were entered into the database at the time of the evaluation. The patients were asked the date of the onset of renal colic and medical records, when available, were used for confirmation. The date of arrival into theater was supplied by the patient and was crossreferenced with the Joint Theater Personnel Roster. The stone location, laterality, number, and size and other pertinent radiographic findings were documented. A history of stone disease was not exclusionary, but patients who had undergone treatment for stone disease in the 30 days immediately before deployment, and patients presenting with a second or subsequent episode of stone disease since arriving in Southwestern Asia, were excluded from the analysis of the time interval. 498

2 Treatment Of Urinary Calculi at the 47th CSH during OIF Urinalysis Chemstrip ( dipstick ) urinalysis was performed when clinically indicated and results were recorded in the database. Urinalysis was not repeated if the results from a referring facility were adequately documented. The study patients were compared to 292 controls comprised of outpatients who underwent urinalysis at the 47th CSH during the study period for a diagnosis other than urinary tract infection or urolithiasis. Treatment Outcomes The treatment course and initiation of air evacuation was determined by the treating urologist and dictated by the clinical scenario. For the purposes of this analysis, patients were divided into two initial groups. The first group consisted of patients manifested for evacuation during their first evaluation at the 47th CSH. The indications for air evacuation included failure of inpatient management and/or stone characteristics, radiographic findings, or concomitant medical conditions not conducive to conservative therapy. Inpatient management consisted of intravenous and/or oral hydration, pain control, and treatment for constipation (a common finding in this patient population). Because many patients required hospital admission for logistical reasons (i.e., awaiting transport), admission did not equate to treatment failure. Patients were considered to have failed inpatient management if they had pain and/or nausea/emesis that required intravenous therapy for longer than 48 hours. Patients who failed inpatient management were not candidates for conservative management. The second group consisted of patients given a trial of conservative outpatient management and returned to duty. Conservative therapy was initiated for patients with stones 4 mm or less in size, who could hydrate well, and whose pain was controlled with oral medications. The size criterion was selected based on published rates of spontaneous stone passage. 5 7 Conservative therapy consisted of 2 to 3 weeks of duty restrictions, oral narcotic pain management, and hydration. All patients were instructed to return for repeat evaluation by a urologist at the 47th CSH even if their symptoms resolved, and they were issued appropriate documentation for their chain of command. Patients who received an initial trial of conservative management were further divided into patients with radiographic evidence of spontaneous stone passage, patients who failed to pass their stones, and patients who were lost to follow-up. Successful conservative management was defined as documentation of stone passage on follow-up radiography. The U.S. Transportation Command Regulating and Command and Control Evacuation System (TRAC2ES) was searched by name and social security number for records that matched patients in the study database and the matching records were reviewed. TRAC2ES records for medical condition other than urinary calculi and TRAC2ES records documenting transfer for the purposes of demobilization were eliminated from analysis. Statistical Methods The arithmetic mean and range were calculated for the age. Stone size and number were compared using an unpaired Student s t test with a two-tailed distribution. The locations of the stones were compared using a 2 test of distribution. The time interval until the development of symptomatic urinary calculi TABLE I MILITARY AFFILIATION OF PATIENTS Affiliation No. of Patients U.S. Army 132 U.S. Marine Corp 30 Civilian 8 U.S. Navy 7 U.S. Air Force 2 Affiliation unknown 2 U.K. Army 1 Total 182 was calculated for each patient by subtracting the date of entry into Southwestern Asia from the date of onset of symptoms. Histograms were constructed for the time interval and the date of the onset of symptoms. SD, mean, median, skew, SE of skew, kurtosis, and SE of kurtosis were calculated for the time interval. The distribution of the time interval was evaluated with the Kolomogrorov-Smirnov test, which compares the data set to a normal distribution. An insignificant p value from the Kolomogrorov-Smirnov test signifies the data set is not statistically different from the normal distribution. SPSS software was used to compute the results. Results 499 From March through August 2003, 182 patients with symptomatic urolithiasis were evaluated at the 47th CSH and entered into the database. One hundred sixty-eight patients were male, 14 were female, and the mean age of the patients was 33.1 years (range, 9 59 years.) The service affiliations are shown in Table I. Stone Location, Size, and Laterality Of the 182 patients with urinary calculi, 159 patients had stones only in the ureter, 5 had stones only in the intrarenal collecting system and/or renal pelvis (herein referred to as renal stones), and 16 had simultaneous renal and ureteral stones. The remaining two patients had incidental renal masses in addition to their calculi. One patient had a left ureteral stone and left renal mass, and one had bilateral renal stones and a right renal mass. Other radiographic findings included an asymptomatic calyceal diverticulum containing stones, an asymptomatic ureteropelvic junction obstruction with ipsilateral renal stones and a contralateral ureteral stone, a ureterocele containing a stone, and a partial duplication of the ureter with a contralateral ureteral stone. Twenty-two renal stones and 184 ureteral stones were recorded for a total of 224 stones. There was no side predominance for the renal or ureteral stones. The difference in size between the right- and left-sided renal stones (9.43 mm and 6.69 mm, respectively), and the right and left-sided ureteral stones (3.87 mm and 3.69 mm, respectively) was not statistically significant (p and p 0.923, respectively). The difference in size among the locations of ureteral stones (e.g., ureteropelvic junction, proximal, mid, distal, and ureterovesical junction (UVJ) stones) was also not statistically significant (p 0.1 for all categories). The anatomic locations of the ureteral stones are tabulated in Table II. There was a statistically significant predominance of lower ureteral stones. At the time of diagnosis, 30% of the right and 33% of the left ureteral stones

3 500 Treatment Of Urinary Calculi at the 47th CSH during OIF TABLE II ANATOMIC DISTRIBUTION OF URINARY CALCULI Anatomic Location Right Left Ureteropelvic junction 5 5 Proximal ureter Mid ureter 4 1 Distal ureter 26* 29* UVJ 34* 42* Recently passed 6 2 Location not annotated 1 1 Total The distribution of ureteral calculi demonstrates a predominance of lower ureteral stones. were located in the distal ureter, and 40% of the right and 47% of the left ureteral stones were located in at the UVJ (p 0.05, bilaterally, 2 ). Time Interval Of the 182 patients entered into the database, 9 patients were excluded from the time interval analysis for the following reasons: 3 patients had undergone treatment for stone disease less than 30 days before their arrival to southwestern Asia, 1 patient presented with his second episode of renal colic since moving to Kuwait 2 years before, and 5 patients had incomplete dates. For the remaining 173 patients, the date of the onset of the symptoms and the date of arrival to southwestern Asia were used to calculate the time interval until development of symptomatic urinary calculi. A detailed analysis of the time interval has been published 8 and a summary of the results is presented here. The dates of the onset of symptoms were randomly distributed (Fig. 1). The dates of arrival into theater (data not shown) mirror the build-up of personnel in anticipation and support of OIF. The time interval until formation of symptomatic urinary calculi is shown in Figure 2. The mean interval is 93 days, the median interval is 91 days, and the SD is 42 days. The skew and SE of skewedness are 0.55 and and the kurtosis and SE of kurtosis are 0.47 and 0.744, respectively, and indicate the data set is skewed slightly to the right, but is mesokurtic. The Kolomogrorov-Smirnov test reveals the time interval approximates a normal distribution (p 0.2). Imaging The diagnostic imaging modality was recorded in 154 patients and the distribution is summarized in Table III. Computerized Fig. 1. The date of the onset of symptoms of urinary calculi follows a random distribution. To facilitate comparison to Figure 2, the dates are shown in intervals of weeks. Fig. 2. The interval to formation of symptomatic urinary calculi follows a normal distribution with a mean of 93 days. TABLE III DIAGNOSTIC IMAGING MODALITY Imaging Modality No. of Patients (%) CT 105 (68) Intravenous pyelography 37 (24) Plain film of the abdomen 8 (5) Retrograde pyelography 4 (3) Total 154 While CT was the most frequent modality used to diagnose stones, a variety of imaging techniques were diagnostic. tomography (CT) was the most common diagnostic modality used at the 47th CSH. Urinalysis The results of the chemstrip urinalysis were recorded for 122 study patients. When compared to the results from 292 control patients, there was no statistically significant difference between the mean specific gravity (control vs. stone , p 0.8 t test) and the mean ph (control vs. stone , p 0.36 t test) of the control and the stone patients. Hematuria was a common finding: 26% of control patients dipped positive for hemoglobin compared to 73% of stone patients. This difference in the frequency of hematuria was statistically significant (p 0.001, 2 ). Treatment and Outcomes Figure 3 outlines the initial treatment choices and the resulting disposition. Of the 182 study patients, 109 were given a trial of conservative outpatient management and 73 did not qualify for conservative therapy and were immediately manifested for air evacuation. The reasons for immediate manifestation are summarized in Table IV and include three patients with ureteral stones who required ureteral stent placement at the time of their initial evaluation at the 47th CSH for concomitant sepsis (two) and azotemia unresponsive to vigorous fluid resuscitation (one). Of the 109 patients who underwent a trial of conservative management, 23 failed because of recurrent pain, nausea, and/or emesis necessitating hospital admission, or persistence of the stone on follow-up imaging. Two patients who otherwise would have been managed conservatively were air evacuated for medical conditions unrelated to stone disease. Thirty patients

4 Treatment Of Urinary Calculi at the 47th CSH during OIF 501 Landstuhl, Germany, 22 had two records documenting evacuation through the European Command to the continental United States (CONUS), and 1 patient had three records documenting evacuation through European Command to CONUS and between CONUS MTFs. Fig. 3. At the time of their initial evaluation at the 47th CHS, patients were either manifested for air evacuation or were returned to duty and given a trial of conservative management. Patients managed conservatively were further subdivided into those who passed their stones, those who failed conservative management and required air evacuation, and those who were lost to follow-up. TABLE IV INDICATION OF EVACUATION FROM THEATER Indication for Air Evacuation Number of Patients Ureteral stone(s) 4 mm 47 Large renal stone(s) 4 Renal mass and stone(s) 2 Persistent renal insufficiency and stone 1 Bilateral ureteral stones 1 Ureteropelvic junction obstruction and stone 1 Urinary tract infection/sepsis and 2 ureteral stone Total 58 Ureteral calculi greater than 4 mm in size were the most common indication for air evacuation. had spontaneous passage of their stones documented by repeat radiographs and the remaining 54 patients never returned for follow-up. Of the 182 patients in this study, 54% (n 98) eventually required air evacuation for definitive management of their stones, 16% (n 30) had documented passage of their stones, and 30% (n 54) were lost to follow-up. To our knowledge, no study patient treated with conservative therapy required admission or intervention for azotemia, infection, or sepsis. A search of TRAC2ES database found records for 79 of the 98 patients evacuated from the 47th CSH for urolithiasis. No records were found for the 54 patients lost to follow-up; however, records were also not found for 20% (n 19) of patients known to have been air evacuated from the 47th CSH. This absence of records suggests TRAC2ES may not be a reliable source of data for research. Of the patients with records in TRAC2ES, 58 patients had one record documenting evacuation to either Rota Spain or Landstuhl Regional Medical Center, Discussion This study is the only modern analysis of stone disease in a large, deployed population and is the first study to address the safety and efficacy of conservative management and determine a time interval to the formation of symptomatic urinary calculi. As urologists at the 47th CSH, we were able to capitalize on the opportunity to observe stone disease in personnel deployed to southwestern Asia in support of OIF. During the study period, the 47th CSH was the largest hospital and main evacuation route for the military theater and as such we treated the majority of patients with renal colic requiring definitive diagnosis, subspecialty care, hospitalization, or evacuation. The study period was also notable for rapid turnover of units and personnel, resulting in large fluctuations in the underlying troop population in theater. Although it is tempting to extrapolate our data to imply incidence, prevalence, or individual risk factors for stone disease, we feel that because of the observational design of our study and the fluctuations in personnel, the baseline population cannot be adequately quantified or characterized, and that speculation about the epidemiology of stone disease has the potential to be grossly misleading. We are currently completing a study addressing the epidemiology of urolithiasis in personnel returning from OIF. Our first conclusion is that deployed personnel with urinary calculi can be appropriately and safely managed with an initial trial of conservative outpatient treatment. Despite the fact that many of our patients were referred from other medical facilities, 60% of the study patients met criteria for conservative management. We feel it reasonable to assume that the percentage of patients who qualify for conservative management would be even higher in the deployed population as a whole. We also believe that our data support the assertion that conservative management is safe. Of 182 patients referred to the 47th CSH for treatment or diagnosis of stone disease, only three required interventions for serious stone-related condition. To the best of our knowledge, no patient given a trial conservative outpatient management by the 47th CSH went on to require admission or intervention for sepsis, infection, or azotemia and this assertion is supported by the theater-wide air evacuation records in TRAC2ES. The success of conservative treatment in the deployed population is likely higher than documented by our study because of the stringent criteria we used to define success. Stone passage was radiographically documented in 30 patients. These patients comprise 28% of the 109 patients treated conservatively and 56% of the 55 patients treated conservatively in whom we had follow-up. Comparable studies of urinary calculi in the general population report spontaneous stone passage rates of 38 to 83% for stones 4 mm or less in size. 5 7 Fifty percent of the patients treated conservatively, which equates to 30% of the study population, were lost to follow-up and their final dispositions are unknown. Although we do not presume that the absence of follow-up implies success of con-

5 502 Treatment Of Urinary Calculi at the 47th CSH during OIF servative therapy, it is important to note that at the time of this study the 47th CSH was the main evacuation route out of theater and few patients could have circumvented our facility. Also of note, a search of the TRAC2ES database did not find air evacuation records for any study patient lost to follow-up. We also acknowledge that the lack of follow-up may not necessarily equate to treatment failure. Some patients may have elected not to follow-up because they passed their stones and their symptoms resolved, and some may have elected to follow-up at more proximal MTFs. The high percentage of patients lost to follow-up in this study highlights the challenge of close medical follow-up during combat and combat like conditions. Based on our data, we conclude that conservative management remains a safe and reasonable option for the initial treatment of stone disease when the operational tempo and theater infrastructure are conducive to appropriate duty restrictions and prompt medical follow-up. The younger age, male predominance, and distribution of military branches of the patients mirrored the demographics of the underlying population. The analysis of the stone demographics demonstrated no predominant side for ureteral or renal stones and no statistically significant difference in the size of stones between the left and right kidneys or among the locations in the ureters. The predominance of distal ureteral stones was statistically significant, but is consistent with the pattern of distribution reported in other studies. 5 7 Hematuria was a frequent finding in deployed personnel seeking medical attention, but was significantly more frequent in personnel with symptomatic urinary calculi (26 vs. 73%, respectively.) The specific gravity and urine ph were not significantly different between the control group and the stone patients. We observed, with interest, that many patients attributed their various genitourinary maladies, to include stone disease, to the mineral content of the bottled water. We would like to debunk the myth that bottled water contributed to urolithiasis. A poll of five camps with large troop populations at the time of the study (two in Kuwait and three in Iraq) identified three dominant suppliers of bottled water and revealed the water to contain 18 to 64 mg of calcium per liter of water a relatively low amount of calcium especially compared to other dietary sources. For example, an 8-oz serving of low fat milk contains 300 mg of calcium. The impact of mineral content of drinking water on urolithiasis remains an esoteric debate among urologists, however, we feel that bottled water is not a significant risk factor for urolithiasis. Anecdotally, many people reported they limited their consumption because of temperature and/or taste of the drinking water or inaccessibility of a bathroom. Dehydration and other dietary factors, such as oxalate and caffeine consumption, are likely the most significant risk factors for urolithiasis in deployed personnel We endorse the command s emphasis on adequate hydration and recommend deployed personnel curtail their consumption of oxalate and caffeine-containing beverages. CT was the most common modality used to diagnose urinary calculi at the 47th CSH, but a variety of imaging techniques were diagnostic in the study population. CT is the community standard for diagnosing calculi because it is quick, sensitive, and provides superior anatomic detail. We do not feel, however, that CT is indispensable for the management of stone disease on the battlefield. Although smaller calculi and uric acid stones are more readily seen on CT, the other information gained by CT did not change the management of the overwhelming majority of stone patients insomuch that no definitive treatment for urinary calculi was available in theater at the time of our study and patients who failed conservative management were air evacuated regardless of stone size. The CT scanner also required a significant amount of power, maintenance, and manpower to remain operable in the austere desert environment. We feel that the small number of patients (n 3) in this study who required intervention because of sepsis or azotemia supports our assertion that clinical acumen paired with alternative imaging techniques, such as intravenous pyelography and plain film radiography of the abdomen, are safe and sufficient means to diagnose and initiate treatment for urolithiasis on the battlefield. It is our opinion that CT scanners should be reserved for larger medical units with infrequent movements on the battlefield and with the resources to maintain and operate a CT scanner. The time interval to formation of symptomatic urinary calculi in our study population had a mean of 93 days, SD 42 days, and followed a normal distribution. This interval is comparable to epidemiologically based studies of the general population and a detailed discussion of these results has been published. A review of the English literature found one article evaluating stone disease in a similar population. In 1945, Pierce and Bloom 13 reported their observations of stone disease in American soldiers deployed for 18 months to an undisclosed desert environment. The authors reported the peak incidence of stone disease (6 of 45 patients) occurred at the 10th month. By comparison, our study revealed a mean time interval that corresponded to the 13th week or the 3rd month. The most likely causes for this difference are changes in diagnostic capabilities and referral patterns since World War II. A confounding factor in this study is the unknown affect of combat on stone formation, stone passage, and referral patterns. Despite censoring patients with a history of treatment for stone disease immediately before deployment, our study population may have contained personnel who, despite medical screening, had undetected urinary calculi before deployment. This study was also subject to selection bias: undoubtedly, there were personnel with urolithiasis who passed their stones spontaneously after their unit medical officer initiated a trial of outpatient therapy. The results of this study, to include the success of conservative therapy and time interval to formation of urinary calculi, may be impacted by the exclusion of these personnel. Finally, acclimatization, or lack thereof, may have influenced the results of this study even though the underlying population included personnel who had been in southwestern Asia for 10 month or longer at the initiation of this study. Conclusions Conservative management of stone disease in deployed personnel is a safe and reasonable option when the mission and situation allows ready and reliable medical follow-up. Sixty percent of patient with stone disease evaluated at the 47th CSH met criteria for conservative management. Of the patients treated conservatively, 28% passed the stones spontaneously, 21% failed conservative management and were evacuated, and 50% failed to return for follow-up. CT was the most frequently used imaging modality at the 47th CSH and the predominance of

6 Treatment Of Urinary Calculi at the 47th CSH during OIF stones was in the distal one-third of the ureter. The mean interval to formation of symptomatic urinary calculi was 93 days or approximately 3 months. References 1. Frank M, Atsmon A, Sugar P, De Vries A: Epidemiological investigation of urolithiasis in the hot arid southern region of Israel. Urol Int 1963; 15: Kotinis-Zambakas SJ: Climatic characteristics of the high urinary tract calculi areas all over the world. Geogr Med 1990; 20: Ramello A, Vitale C, Marangella M: Epidemiology of nephrolithiasis. J Nephrol 2000; 13(Suppl 3): Salem SN, Phil D, Abu Elezz LZ: The incidence of renal colic and calculi in Kuwait: an epidemiological study. J Med Liban 1969; 22: Coll DM, Varanelli MJ, Smith RC: Relationship of spontaneous passage of ureteral calculi to stone size and locations as revealed by unenhanced helical CT. Am J Roentgenol 2002; 178: Miller OF, Kane CJ: Time to stone passage for observed ureteral calculi. J Urol 1999; 162: Hubner WA, Pierce I, Stoller M: Natural history and current concepts for the treatment of small ureteral calculi. Eur Urol 1993; 24: Evans K, Costabile RA: Time to development of symptomatic urinary calculi in a high-risk environment. J Urol 2005; 173: Prince CI, Scardino PL, Wolan CT: The effect of temperature, humidity, and dehydration on the formation of renal calculi. J Urol 1956; 75: Borghi L, Meschi T, Amato F, et al: Hot occupation and nephrolithiasis. J Urol 1993; 150: Borghi L, Meschi T, Amato F, et al: Urinary volume, water and recurrence in idiopathic calcium nephrolithiasis: a 5-year randomized prospective study. J Urol 1996; 155: Pin NT, Ling NY, Siang LH: Dehydration from outdoor work and urinary stones in a tropical environment. Occup Med 1992; 42: Pierce LW, Bloom B: Observations on urolithiasis among American troops in a desert area. J Urol 1945; 54: