The following expert report from a Phospho-Soda lawsuit filed in West Virginia explains how Phospho-Soda causes kidney failure. The report also gives some of the regulatory history of the product.
The report is from Dr. Karen Kim, M.D., a professor at the University of Chicago Medical Center.
As per our conversation, I am providing my expert review on the File No.: 519-1042 (Burk v. C. B. Fleet Corporation). I am board-certified in internal medicine and gastroenterology. I have been a faculty member at the University of Chicago Medical Center for the past 12 years, where I am currently an Associate Professor of Medicine. During this tenure, I have had multiple roles including Director of the Colon Cancer Screening Program and Co-director of the GI Fellowship Program. Additionally, I am chair of the American Cancer Society (Illinois Division) Early Detection and Prevention Committee. I am actively involved in research on colorectal cancer screening uptake and in these capacities, have tremendous experience and expertise in gastroenterology, with a particular focus on colonoscopy for cancer screening. In addition, I teach colonoscopy to GI fellows and perform approximately 20-25 colonoscopies per week.
I have reviewed the medical records, depositions and case records provided by your office with regards to the claims brought by Walter Burk against the C. B. Fleet Company, Inc. Mr. Burk states that he drank the Fleets Phospho-soda preparation (FPS) on January 11, 2005 in order to cleanse his colon prior to a EGD/colonoscopy on January 12, 2005. Mr. Burk states that shortly after this ingestion, he sustained serious and permanent injury to his kidneys, as a direct and proximate result of drinking the FPS.
I have reviewed the following documents: Complaints, medical records, including all laboratory data, endoscopic records, inpatient and outpatient notes and medication lists and bowel preparation orders. I have reviewed the expert opinions of Drs. Levenson, Markowitz, Parisian, Blume and Moore. Additionally, I have reviewed the literature and product information provided by your office.
The opinions herein are rendered within a reasonable degree of medical certainty.
Mr. Burke was admitted for evaluation of chronic nausea and abdominal pain on January 10, 2005. He was seen in consultation by a gastroenterologist and was scheduled for a colonoscopy/EGD for evaluation of his symptoms. In the inpatient orders, he was prescribed a FPS prep the day before his procedures, to be taken at 1600 and again at 2100, in addition to a clear liquid diet. He underwent a combined EGD and colonoscopy on January 12, 2005, which revealed a hiatal hernia, gastritis, non-specific inflammation in the colon and a polyp. No intraoperative records were available for review. At the time of his admission, Mr. Burk was a 68 year old man with a history of hypertension, hyperlipidemia, diabetes, prostate cancer, pituitary adenoma, chronic nausea and abdominal pain and depression and was on norvasc, prozac, phenergan, nexium, alprazolam and carafate. His admission creatinine was 0.6 mg/dl. He was discharged from the hospital on January 13, 2005. Mr. Burk underwent another EGD with endoscopic ultrasound on 3/23/05, and was diagnosed with a benign leiomyoma. He had office visits with Dr. Newland on 7/18 and 7/27/05 for persistent complaints of nausea and abdominal pain and was found to be hypertensive. On 9/29/05, Mr. Burk was admitted for rectal bleeding, and he was found to have a serum creatinine of 7.4 mg/dl. A renal ultrasound on 10/1/05 showed echogenic kidneys without evidence of renal artery stenosis and a kidney biopsy on 10/3/05 was interpreted as severe nephrocalcinosis with prominent interstitial fibrosis and tubular atrophy. Since his diagnosis of acute and chronic renal failure, Mr. Burk required hemodialysis and was evaluated for possible renal transplantation.
Evidence for Colorectal Cancer Screening
In the United States, colorectal cancer (CRC) is-the third most common cancer diagnosed in men and women and the second leading cause of death from cancer. In 2008, it is estimated that 148,810 men and women will be diagnosed with CRC and 49,960 will die from this disease. Five-year survival is 90% if the disease is diagnosed early, but unfortunately, the majority of colorectal cancers diagnosed in the US are not diagnosed at their earliest stage. Although prospective randomized trials and observational studies have demonstrated mortality reductions associated with early detection of disease, the majority of US adults is not receiving regular age and risk-appropriate screening or has never been screened at all. While numerous modalities exist for screening, direct visualization of the colonic mucosa allows for the removal of potential pre-malignant polyps, decreasing one's risk of the development of CRC. Colonoscopy has been the ‘gold standard’ for this screening process. Colonoscopy is one of the most commonly performed medical procedures in the United States, with over 14 million procedures performed in 2003. Studies have shown that the effectiveness of colonoscopy as a screening tool is highly dependent upon numerous factors including experience, withdrawal time, co-morbid conditions and proper bowel preparation, specifically bowel cleansing, a critical element in the accuracy and cost-effectiveness of screening. Adequate bowel preparation has been shown in the medical literature to be associated with greater polyp detection, faster procedure times, and reduced complications including bowel perforation and sepsis risk (Harewood, 2003, Froehlich, 2005, Bond, 2007). Oral sodium phosphate solution (OSPS) is commonly used for bowel preparation for colonoscopy. Review of individual trials indicate that OSPS is as or more effective and as or better tolerated than PEG-ELS. OSPS was equal to PEG in bowel prep quality in 12 trials and superior to PEG in 10 trials. In 18 trials reporting “ease of use,” OSPS was rated as better than PEG, and in 6 trials there was no significant difference. A meta-analysis found OSPS to be as efficacious and better tolerated than PEG-ELS. Translating these finding into clinical practice are the main reasons to have choice in bowel preparation. When patients cannot tolerate the bowel preparation, adherence rates decline, and complication rates increase; including perforation, missed lesions prolongation of the procedure and the need for multiple exams. Therefore, risk/benefit ratios must be carefully weighed in choosing both the modality of screening as well as the bowel preparation.
Applicable professional Labeling:
Although FPS is an over the counter product, prior to 2005, the OTC product label clearly warned patients that doses greater than 45 ml in 24 hours can be harmful and should be directed by a physician. The label also states ‘do not use this product if you have kidney disease or on a sodium restricted diet, unless directed by a physician’. While the product labels outlined these risks, the standard pre-colonoscopy protocol is for the provider to provide either written or oral instructions for bowel preparation, which are followed by patients prior to their procedure. In Mr. Burk's case, it is not clear how FPS was administered, although the hospital orders spaced the two doses apart by 5 hours. No instructions were available regarding fluid ingestion during the bowel preparation.
What is clear in the literature regarding oral sodium phosphate preparation for bowel cleansing is that it is a safe and effective when used in patient without significant co-morbid conditions together with physicians providing specific instructions to such patients that appropriately direct the amount and timing of the doses and adequate hydration to replace the volume lost during the bowel cleansing process, as outlined herein. Prior to September 2003, the medical community was certainly aware of case reports describing patients who had sustained renal failure and electrolyte fluctuations, among other complications, following use of a oral sodium phosphate based bowel preparation. These reports primarily described patients who were overdosed or with relative contraindications.
What has been known for years is that potential complications from use of such bowel preparations include hypotension, renal failure and electrolyte abnormalities. Therefore, physicians have been instructed to carefully risk stratify patients to determine which colon cleansing preparation is safe. While the medical community has been aware of these risks, between 2003 and 2005, a series of case reports described specific histological findings of nephrocalcinosis associated with acute renal failure following the use of oral sodium phosphate preparations. No literature reports were found describing use of a sodium phosphate bowel cleansing agent associated with nephrocalcinosis prior to that time. The authors suggested strategies to prevent renal failure post ingestions including adequate hydration. Additionally, since many of the cases resulted in renal failure in patients on NSAIDs and anti-hypertensive therapy with ACE-inhibitors or ARBs, they suggested avoiding use of these drugs on the day prior to and the day of the colonoscopy. Additionally, they recommended that oral phosphate solutions must be used with great caution in the elderly. While these studies are important to recognize, it is imperative to interpret these results in terms of the accuracy of retrospective case reports, since these are retrospective, convenience sampling, there is no adequate way to control potential confounding variables. Despite the nature of this level of evidence, the C.B. Fleet Corporation continued to update their product information to reflect the potentially changing safety profile of Fleet's Phospho-Soda, through the PDR product warnings, letters to health professionals and product labeling.
In May 2002, C.B. Fleet Company, Inc sent important prescribing information for Fleet Phospho-Soda to Health professionals. The letter reiterated the safe and effective use of FPS as a bowel-cleansing agent, but cautioned providers about potential electrolyte and vascular volume effects, particularly with improper use. Specifically, the letter reported that FPS should not be used in patients with:
Megacolon, Kidney disease, Congestive Heart failure, Bowel Obstruction or ascites.
Additionally, FPS should be used with caution in patents with: Impaired renal function, heart disease/failure, acute MI, unstable angina, pre-existing electrolyte disturbances or increased risk of electrolyte disturbance, and in patients taking drugs that prolong the QT interval.
Specifically, the company specified that patients at risk for electrolyte disturbance include those with:
GI obstruction, gastric retention, bowel perforation, colitis or ileus, or who are dehydrated, debilitated, unable to take adequate fluid, or taking diuretics or other medications that affect electrolytes.
Furthermore, the letter suggested that electrolyte imbalance can lead to acidosis, tetany, cardiac arrhythmias, dehydration, renal failure and hypovolemia and in rare cases, death, particularly if more than 45 ml of the FPS is given in less than 24 hours. In those patients at risk, they recommended obtaining a baseline and post treatment biochemical profile.
The applicable professional labeling available for FPS in the 2004 PDR in pertinent part advises healthcare professionals:
Do not use in patients with megacolon, gastrointestinal obstruction, ascites, congestive heart failure, kidney disease or in children under 5 years of age.
Additionally, FPS should be used with caution in patents with:
Impaired renal function, heart disease/failure, acute MI, unstable angina, pre-existing electrolyte disturbances or increased risk of electrolyte disturbance (e.g. dehydration, gastric retention, bowel perforation, colitis, ileus, inability to take adequate oral fluid, concomitant use of diuretics or other medications that affect electrolytes), with debilitated or elderly patients or with patients taking drugs that prolong the QT interval.
Medical providers are also advised to not use any other sodium phosphate preparations concomitantly. Such concomitant sodium phosphate based laxatives would include Fleet enemas.
C.B.Fleet further advised physicians that in such:
at-risk patients, including elderly patients, consider obtaining baseline and post-treatment sodium, potassium, calcium, chloride, bicarbonate, phosphate, blood urea nitrogen and creatinine values, and consider using the lower end of the dosage range. There is a risk of elevated serum levels of sodium and phosphate and decreased levels of calcium and potassium: consequently, hypernatremia, hyperphosphatemia, hypocalcemia, hypokalemia, and acidosis may occur”
In 2005, the PDR Professional Use Warnings and Precautions were as follows:
Do not use in patients with megacolon, gastrointestinal obstruction, ascites, congestive heart failure, kidney disease or in children under 5 years of age.
Use with caution in patients with impaired renal function, heart disease, acute myocardial infarction, unstable angina, pre-existing electrolyte disturbances, increased risk for electrolyte disturbances (e.g., dehydration, gastric retention, bowel perforation, colitis, ileus, inability to take adequate oral fluid, concomitant use of diuretics or other medications that affect electrolytes), with debilitated or elderly patients or with patients who are taking medications known to prolong the QT interval.
In at-risk patients, including elderly patients, consider obtaining baseline and post-treatment sodium, potassium, calcium, chloride, bicarbonate, phosphate, blood urea nitrogen and creatinine values, and consider using the lower end of the dosage range. There is a risk of elevated serum levels of sodium and phosphate and decreased levels of calcium and potassium; consequently, hypernatremia, hyperphosphatemia, hypocalcemia, hypokalemia, and acidosis may occur. Additional fluids by mouth are recommended with all bowel cleansing dosages. Encourage patients to drink large amounts of clear liquids to prevent dehydration. Drinking large amounts of clear liquids also helps ensure that the patient's bowel will be clean for the procedure. No other sodium phosphate preparations should be given concomitantly.
In addition, the bolded warnings were as follows:
TAKING MORE THAN THE RECOMMENDED DOSE IN 24 HOURS CAN BE HARMFUL. IF THERE IS NO BOWEL MOVEMENT AFTER MAXIMUM DOSAGE, CONTACT A PHYSICIAN AS DEHYDRATION COULD OCCUR. SINCE FLEET PHOSPHO-SODA IS AVAILABLE IN TWO SIZES, PRESCRIBE BY VOLUMES. DO NOT PRESCRIBE “BY THE BOTTLE” AS SERIOUS SIDE EFFECTS FROM OVERDOSAGE MAY OCCUR.
The 2005 PDR also included a section on overdose as stated below:
Overdosage or retention of FLEET Phospho-soda may lead to severe electrolyte disturbances, including hyperphosphatemia, hypernatremia, hypocalcemia and hypokalemia, as well as dehydration and hypovolemia, with attendant signs and symptoms of these disturbances (such as metabolic acidosis, renal failure and tetany). Certain severe electrolyte disturbances may lead to cardiac arrythmias and death. The patient who has taken an overdose should be monitored carefully. Treatment of electrolyte imbalances may require immediate medical intervention with appropriate electrolyte fluid replacement.
In 2006, a consensus (American Society of Gastrointestinal Endoscopy, American Society of Colorectal Surgeons, Society of American Gastrointestinal and Endoscopic Surgeons) document of bowel preparation before colonoscopy was reported in Gastrointestinal Endoscopy, 2006. It stated the oral sodium phosphate was an equal alternative to PEG with the following exceptions:
Pediatric and elderly patients, patients with a bowel obstruction, gut dysmotility, renal failure, congestive heart failure, liver failure. Furthermore, it recommended using a PEG based solution in children, elderly patients, patients with renal insufficiency and those with hypertension who are taking ACE inhibitors or ARBs.
Furthermore, the editorial board from Gastrointestinal Endoscopy from 2006 concluded that it is reasonable to continue use of oral sodium phosphate regimens for patients without contraindications or other concerning risk factors.
Information regarding the risk/benefits of oral sodium phosphate solutions for bowel preparation were clearly available to physicians prior to and including 2005, and warned physicians about potential complications in patients with specific conditions, many of which Mr. Burk had prior to his colonoscopy. Mr. Burk's potential risks included hypertension, advanced age, and diabetes. These multiple risk factors placed Mr. Burk at an increased risk for complications from FPS use. Despite these multiple risk factors, Mr. Burk's gastroenterologist chose FPS as her bowel cleansing preparation. While physicians are often aware of potential complications when prescribing medications to their patients, this is done in the context of weighing the risk to benefit ratio. Given Mr. Burk's multiple risk factors, the professional use warning information available for FPS prior to and in 2005, and the availability of alternative bowel cleansing preparations, use of FPS in Mr. Burk was a high risk decision. This risk could have been reduced with adequate hydration and increasing the interval between doses, which according to the instruction orders, were not specifically addressed. Furthermore, Mr. Burk underwent two endoscopic procedures on the same day, potentially lengthening his exposure to anesthetic agents. Whether he had a significant drop in BP during the procedure or suffered from periods of relative hypoxemia, both which may have contributed to his post-operative renal failure was not available in the medical records provided.
While it is not clear what precipitated Mr. Burk's acute renal failure and subsequent chronic renal failure, numerous potential etiologies exist including, but not limited to: age, chronic uncontrolled hypertension, diabetes, failure to adequately hydrate during his bowel preparation and the short interval between doses prescribed. Additionally, it is unclear what other medical problems may have added or caused Mr. Burk's acute and chronic renal failure, since 8 months passed between his endoscopy and bowel preparation and the onset of documented renal disease.
What is clear is that based upon the information that was available to health professional in 2004 and 2005, provided by C.B. Fleet, medical literature and discussions at national professional meetings, Mr. Burks healthcare providers had sufficient medical information to make an informed and appropriate medical decision regarding his bowel preparation, and decided to proceed with FPS use despite these warnings. I believe that in 2005, Mr. Burk was not a good candidate for the oral FPS use and dosing as administered by his physicians.
If called to testify, I will specifically address issues pertaining to screening colonoscopies, colorectal cancer screening, and issues relating to the field of gastroenterology. Specifically I will discuss the medical issues related to Mr. Burk.
I reserve the right to amend or supplement the report as further information may become available
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