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Natural History of Asymptomatic Gallstones in Family Practice Office Practices
Jennifer Zubler, MD;
Geoffrey Markowski, MD;
Sandra Yale, DO;
Robin Graham, PhD;
Thomas C. Rosenthal, MD
Arch Fam Med. 1998;7:230-233.
ABSTRACT
Background Improved access to less invasive testing has resulted in more Americans being diagnosed with asymptomatic gallstones. The family physician has had to rely on community-based or referral patient studies to advise their office-based patients about treatment options.
Objective To understand the natural history of asymptomatic gallstones discovered through a routine patient care process in a rural, office-based research network of 9 family physician practices.
Participants and Methods Nine family physician practices agreed to comb their records for medical records of patients found to have asymptomatic gallstones during their routine primary care practice. Medical records were then reviewed annually for 5 years for evidence of gallstone-related problems. Results were compared with previous English-language literature studies.
Results Asymptomatic gallstones were found in 32 patients (19 women [59] and 13 men [41] with an average age of 59.5 years). Symptoms developed in 8 patients (25%) after an average latency period of 3 years 5 months. Seven patients underwent cholecystectomy; there was no gallstone-related mortality in this group. One patient who developed a ruptured gallbladder required an emergency procedure.
Conclusions Routine office practice is detecting only a small percentage of the asymptomatic gallstones expected by community-based screening studies. While more of these patients became symptomatic than in general population studies, most patients with asymptomatic gallstones required no treatment. Those patients in family practice offices who are serendipitously found to have gallstones can generally be followed up conservatively.
INTRODUCTION
APPROXIMATELY 15 to 20 million adults in the United States have gallstones, most of which are asymptomatic.1-3 Earlier this century, when little was known about the natural history of gallstones, it was recommended that all gallstones be surgically removed.4-5 This recommendation assumed that asymptomatic gallstones would eventually become symptomatic and that elective cholecystectomy would lower morbidity and prevent gallbladder cancer.6 While symptomatic gallbladder disease is an accepted indication for surgery, more recent studies disclose that only 10% to 18% of asymptomatic patients ever develop symptoms.7 When symptoms do develop, they usually begin as non–life-threatening biliary colic within 5 years of the original diagnosis.8 With modern surgical techniques, cholecystectomy after symptoms develop results in a mortality rate almost equivalent to elective cholecystectomy.2, 9-14 Liberal use of ultrasonographic scanning has added to the discovery frequency of abdominal x-ray films, oral cholecystograms, and surgery.15
This article reflects the efforts of a rural, office-based, research network of 9 family physicians to understand the natural history of asymptomatic gallstones discovered through their own routine patient care process. Unable to find studies of patients with asymptomatic gallstones in an unscreened, unreferred, office-practice population, these physicians participated in a multioffice medical record review and 5-year follow-up that tracked the following: the method of diagnosis, treatments, outcomes, and predictive variables for the development of symptoms and complications, comparing their findings with published articles about asymptomatic patients.
PARTICIPANTS AND METHODS
Nine family practice practices belonging to the Rural Research Network of Western New York agreed to review their medical records and identify patients with asymptomatic cholelithiasis. In each participating office the head nurse was asked to screen all medical records to identify patients with cholelithiasis. The nurse was then paid a small stipend for each case discovered. Comprehensiveness of the search was enhanced in those offices with computer billing systems that tracked secondary diagnoses and one physician practice included ultrasonographic scanning services for which careful logs were kept.
Using a survey instrument designed for this project, patient medical records were reviewed for the method of diagnosis and the presence of symptoms at the time of discovery. Patients were considered symptomatic if any abdominal pain possibly referable to the gallbladder or gallstones had been documented in the medical record. Patients were considered asymptomatic if there was no history of abdominal pain or if there was a documented unrelated explanation for the pain.
Patients with asymptomatic gallstones who were asymptomatic, both at the time of discovery and at the time the study began, were followed up at yearly intervals during a 5-year period from January 1, 1990, through December 31, 1994. Each year the medical records were reviewed to see if the patients had developed symptoms, remained asymptomatic, received treatment, or had complications associated with their gallstones. Results were entered into a commercially available statistical software package (SPSS for PC, SPSS Inc, Chicago, Ill) and, where appropriate, SDs were calculated and significance of the means was estimated using the Student t test.  2 was used to determine significance of the difference in proportions. Statistical significance was set at P<.05.
Using MEDLINE and secondary searching methods, the English-language literature was reviewed from 1978 to April 1997 for study series of asymptomatic patients with gallstones. These studies were then compared with the patients from the rural research network (Table 1).
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Comparison of Published Data on Follow-up of Asymptomatic Gallstone Disease
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RESULTS
The participating family physicians possessed a total of 19980 adult patients' medical records. The search discovered a total of 32 patients (19 women [59] and 13 men [41] [P<.10, 2test]) with documented asymptomatic gallstones for a prevalence of 1.6 per 1000. The average age of patients at the time of gallstones discovery was 59.5 years, with a range of 23 to 86 years (SD=±14 mo). Ultrasonographic scanning was the most common method of discovery. Almost half (47%) of all patients with gallstones (symptomatic or not) were diagnosed by ultrasonographic scanning but 25% of these patients had potentially related complaints (dyspepsia) and were excluded from further analysis in this series. Of the asymptomatic gallstones, ultrasonographic scanning accounted for discovery of 72%. Incidental findings on x-ray films (16%) and during unrelated surgery (9%) were responsible for the remaining cases. No method of discovery was recorded for one case.
The average follow-up period documented in the medical record from the time of gallstone discovery was 5 years 11 months, with a range of 10 months to 16 years 5 months. Three patients were lost to follow-up; there were 7 deaths (22%). All deaths were unrelated to gallstones or to their treatment. The average age at the time of death was 73 years, ranging from 58 years (due to myocardial infarction) to 94 years.
A total of 8 patients (25%) developed symptoms at some point during follow-up period. The average latency period from the time of discovery of gallstones until the onset of symptoms was 3 years 5 months (SD=±6 years.). One patient had a latency period as short as 4 months and for another symptoms began 7 years 8 months after discovery. The average age at onset of symptoms was 69.4 years, with a range of 57 to 89 years (SD=±13 years). All patients experienced symptoms consistent with biliary colic as their initial presentation, except for an 89-year-old patient who presented with a ruptured gallbladder. The longest documented period of asymptomatic gallstones was 16 years 5 months. Patients who remained asymptomatic were only somewhat younger on average than those who developed symptoms, 57.6 years compared with 66.1 years (P>.05, Student t test). Women were more likely to become symptomatic than men (7 women, 1 man, respectively) (P<.05, 2test).
Cholecystectomies were performed on 7 patients (22%), 5 patients (16%) had developed symptoms and 2 patients (6%) who underwent elective procedures without symptoms. Only the patient with the ruptured gallbladder underwent emergency surgery. The remaining surgical procedures were nonurgent. There were no deaths and minimal morbidity associated with any surgical procedures. One patient suffered postoperatively from a persistent right upper quadrant pain and tenderness.
Three of the 8 patients who developed symptoms declined surgery. When compared with those who declined surgery, those who had surgery had symptoms for a somewhat shorter period (±SD), 24±17 months vs 63±45 months (P>.10, Student t test) but were about the same age (68 vs 70 years) with each group experiencing 1 to 3 symptomatic episodes. Those who had surgery were older when their gallstones were discovered (67 vs 55 years).
COMMENT
The incidence of asymptomatic gallstones in the general population has been understood only recently, largely due to the application of ultrasonographic scanning to well populations. Rates as low as 5% in African Americans to as high as 15% in Mexican Americans have been reported.2, 10, 16 A previous study in western New York revealed an incidence of 11%.15 The rate of 0.16% reported herein suggests that many patients with gallstones remain undiagnosed during routine office practice. The accidental discovery of gallstones during medical workups for other conditions discovered fewer cases than would have been predicted. However, there is no evidence to suggest screening more patients would lead to better health care outcomes.15 In fact, if screening more patients leads to increased discovery of gallstones there is a good reason to suspect more patients will undergo unnecessary cholecystectomy as did 2 of these patients.9 The medical workups in this series were ordered on patients presenting for problems unrelated to gallstones but should not be confused with a community-based asymptomatic population because these patients were presenting to a physician's office. Our rural research network physicians were concerned that these patients with unintended gallstone discovery were a unique population of people and perhaps should be followed up differently than randomly screened populations.
Many health problems have been associated with gallbladder disease, including old age, obesity, diabetes mellitus, alcoholism, smoking, and estrogen replacement therapy.16-17 These situations do lead to greater physician contact and more diagnostic testing. The discovery that 25% of the patients became symptomatic is on the high end of the 10% to 33% reported in series of the general population and suggests that those patients seen by the rural research network group may be somewhat more likely to develop symptoms. One study showed a higher symptomatic rate could be explained by the intensive (every 3 months) follow-up in that group (Table 1).9-10,14, 18-19
The discovery phase of this study disclosed that the number of cases found through medical record review was not as large as had been projected from screened community population studies. Secondary sampling of office medical records to ensure cases had not been missed failed to disclose more cases. Because medical record data often underestimate the frequency and intensity of complaints, there was concern about confirming the asymptomatic status. The study design compensated for this concern by considering documentation of any abdominal discomfort, not otherwise diagnosed, as evidence of symptomatic gallbladder disease. However, it is possible that mild episodes of pain went undocumented. To ensure consistency, medical record reviews each year were conducted by the same individual (J.Z.).
The clinicians also questioned whether there was a typical symptom latency period for these patients. In this series, the average latency period for the 8 (25%) of the 32 patients who became symptomatic was 3 years 5 months, but the range was wide (4 months to  8 years). In 1986 Mok et al20 reported a unique group of patients followed up because of exposure to radiation. It took a minimum of 2 years from the time a gallstone appeared in their periodic testing routines for symptoms to develop. Even though other studies have suggested that most patients who develop symptoms do so within a short period, the rural research network's series suggests a need for long-term monitoring.9-10 The literature suggests that carcinoma of the gallbladder is rare enough to warrant no specific follow-up recommendations.10
When considered in context with other studies, this analysis of rural, office-based practice–discovered cases offers modest reassurance that while there may be a 25% incidence of symptom development, watchful waiting results in neither a high morbidity nor a high incidence of emergency surgery. The only emergent case was the 89-year-old patient who presented with a ruptured gallbladder. This undesirable event resulted in a prolonged hospitalization (2 weeks) but a favorable outcome. It is possible that prior knowledge of the presence of gallstones lead to timely diagnosis and is consistent with other studies that have found no significant difference between elective and emergent surgery.11 The rural research network physicians have elected to see asymptomatic patients on an annual basis and carefully review the patients interval history for evidence of biliary colic or other symptoms that may warrant further treatment. Laparoscopic cholecystectomy with its decreased morbidity may offer new options for patients with mild symptoms.
As our diagnostic tests become more accurate, more accessible, and less invasive, family physicians will encounter decisions about asymptomatic conditions more frequently. Ultrasonographic scanning has added considerably to our awareness of gallstones in otherwise well patients and has increased the need to understand the natural history of this disease in all populations. The risk of treatment can, on occasion, exceed the risk of waiting, especially for conditions that require invasive surgical procedures.21 Evidence-based decision making has come a long way since Mayo declared that there was no innocent gallstone.22-23 This article describes one group of physicians' longitudinal attempt to understand their patient population relative to published data. The similarity of results increases the confidence with which physicians can recommend watchful waiting to the asymptomatic patient.
AUTHOR INFORMATION
Accepted for publication April 17, 1997.
This study was supported by a grant from the New York State Academy of Family Physician Foundation, Albany (Dr Rosenthal).
Participating Western New York Rural Research Network Physicians included the following: Donald Brautigam, MD; Gordon Comstock, MD; Dale Deahn, MD; Thomas Dwyer, MD; Jeffrey Hanson, MD; Lori Hudzinski, MD; William Lampard, MD; Herbert Laughlin, MD; Thomas Lawrence, MD; Rodney Logan, MD; Andrea Manyon, MD; J. Thomas Reagan, MD; and Timothy Siepel, MD.
Holmes McGuigan assisted in manuscript preparation.
Corresponding author: Thomas C. Rosenthal, MD, Department of Family Medicine, State University of New York, Buffalo, 462 Grider St, Buffalo, NY 14215.
From the Departments of Pediatrics (Dr Zubler) and Family Medicine (Drs Markowski, Yale, Graham, and Rosenthal), State University of New York, Buffalo.
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