Chronic unexplained diarrhea in human immunodeficiency virus infection: determination of the best diagnostic approach

The influence of hospitalization and HIV severity on gastrointestinal PCR panel evaluation of HIV-related acute diarrhea in New York City: a retrospective, cross-sectional study

INTRODUCTION

Diarrhea is common in persons living with HIV (PLWH)/AIDS. With the increasing utilization of multiplex gastrointestinal PCR panel (GI panel) testing, we aimed to characterize the roles of CD4 count and hospitalization in GI panel assessments of PLWH with acute diarrhea.

METHODS

We performed a cross-sectional study of adult PLWH with acute diarrhea who underwent GI panel testing at two urban academic centers. Demographic, HIV disease, GI panel result, and hospitalization data were collected, and patients were cohorted by CD4 count (CD4 < 200, CD4 200-499, CD4 > = 500). The primary outcome was enteric infection as detected by GI panel, and hospitalization.

RESULTS

Of 298 PLWH, 119 (39.9%) had a CD4 count below 200, 195 (65.4%) were hospitalized, and 137 (46.0%) had enteric infection. Bacterial infection correlated with higher CD4 count (41.9% (CD4 > = 500) vs 31.2% (CD4 200-499) vs 25.2% (CD4 < 200), p = 0.041). Hospitalization correlated with poorly controlled HIV and fewer enteric infections (34.4% vs 68.0%, p < 0.001). After adjusting for HIV disease severity, a negative GI panel remained independently associated with hospitalization (adjusted odds ratio (aOR) 5.32, 95% confidence interval (CI) 2.72-10.9), even in patients tested within 72 hours of hospitalization. Despite better HIV control, men who have sex with men (MSM) had more frequent infectious diarrhea, including from E. coli, giardiasis, and multiple pathogens. MSM status independently predicted enteric infection (aOR 1.93, 95% CI: 1.02-3.67).

CONCLUSIONS

GI panel results vary by HIV disease severity and hospitalization in PLWH. Clinicians - especially in the inpatient setting - should carefully consider these factors when interpreting GI panel results. Further characterization of diarrheal etiology in PLWH with a negative GI panel is needed.

PLAIN LANGUAGE SUMMARY

PCR stool test results are affected by certain factors in HIV-related diarrhea Diarrhea is common in people living with HIV (PLWH) and has a variety of causes, including infections, medications, and HIV itself. Multiplex polymerase chain reaction (PCR) stool testing simultaneously evaluates for a variety of common viral, bacterial, and parasitic infections of the gastrointestinal tract, and is increasingly being used in patients with diarrhea. However, patients with HIV and diarrheal illness may have uncommon infections not typically present in those with normal immune function - and thus not routinely evaluated for in stool testing. It is not known what factors, if any, might affect the results of PCR testing in HIV-related diarrhea.In this study, we examined all PLWH who underwent stool PCR testing for diarrhea over a 4-year period. We separated the patients into groups based on HIV disease severity as measured by CD4 T-cell count, or the count of the immune cells affected by HIV. We examined whether there were differences among groups in infection rates as detected by PCR stool testing. Separately, we studied the role of hospitalization in stool PCR test results.Of 298 PLWH who underwent stool PCR testing for diarrhea, 119 had a CD4 count less than 200 (low CD4 count), 195 were hospitalized at time of testing, and 137 had a positive stool PCR test. Compared to those with a low CD4 count, subjects with less severe HIV disease were more likely to have a bacterial infection on stool PCR testing and less likely to be hospitalized. Hospitalized patients were more likely to have a negative PCR stool test, regardless of CD4 count. Many patients with a low CD4 count had diarrheal etiologies not evaluated by multiplex stool PCR. In PLWH who experience diarrhea, stool PCR testing results vary by CD4 count and hospitalization. Providers should be mindful of these factors when interpreting stool PCR test results.

Cytomegaloviral colitis in HIV positive patients: endoscopic findings

BACKGROUND

Diarrhea in seropositive human immunodeficiency virus patients is one of the most important and disabling symptoms, and often decreases their quality of life. Cytomegalovirus colitis is among the principal causes of this symptom and colonoscopy is the gold standard examination to diagnose it.

AIM

To define the main endoscopic findings in seropositive human immunodeficiency virus patients with cytomegalovirus colitis.

METHODS

Two hundred and forty-three colonoscopies were performed in 200 seropositive human immunodeficiency virus patients with diarrhea associated or not to abdominal pain or gastrointestinal bleeding, over 10-year period, whom 51 patients were diagnosed with cytomegalovirus colitis. Full length colonoscopy with ileum intubation was always tried and multiple biopsies of all segments examined, including endoscopically normal segments, were attempted. All diagnoses were confirmed by histologic and immunohistochemical studies.

RESULTS

Total colonoscopy was possible in 98.03% and ileum intubation in 88.23% of these cytomegalovirus colitis patients. At colonoscopy, a heterogeneous ulcerative pattern was presented in 72.54%, an inflammatory process of the mucosa in 21.56% and 5.88% of the patients mucosa was endoscopically normal.

CONCLUSION

Full length colonoscopy with ileum intubation and multiples biopsies of all segments, even when they are endoscopically normal, have always to be attempted in cases of seropositive human immunodeficiency virus patient with diarrhea.

The role of sigmoidoscopy and colonoscopy in the diagnosis and management of lower gastrointestinal disorders: technique, indications, and contraindications

Flexible sigmoidoscopy and colonoscopy have revolutionized the clinical management of colonic diseases. Colonoscopy has a broad range of indications, including evaluating lower GI symptoms such as lower GI bleeding, evaluating abnormal radiographic findings, and screening and surveillance for colon cancer. Colonoscopy is increasingly being used therapeutically. Patient evaluation, patient instructions, and colonic preparation before colonoscopy are essential for safe and efficient colonoscopy. Intravenous sedation reduces patient pain and anxiety during colonoscopy, but requires monitoring by pulse oximetry and automated measurements of vital signs. An experienced colonoscopist can complete colonoscopy in 90% or more of cases, using maneuvers to maintain the colonic lumen in view, straighten the colonoscope, and avoid looping during colonic intubation.

Infectious diarrhea in human immunodeficiency virus

Chronic HIV-associated diarrhea is currently a field in flux. Improved noninvasive diagnostic tests, improved pathogen-specific regimens, and better empiric therapies may change some of the assumptions used to select algorithms for diagnostic evaluation and management. Any shift in the cause of diarrhea from pathogen-associated to idiopathic or a reduction in the overall incidence of diarrhea would have considerable impact. It is unclear how significant the problem of pathogen relapse in previous responders will become. Existing studies reviewed in this article show that the high diagnostic yield of endoscopy when stool tests are negative, coupled with significantly better outcomes when pathogens are identified, support the current practice of routine endoscopic evaluation. There currently are scant data on the economic impact of HIV-associated diarrhea as it relates to pathogen-specific and empiric therapy in the era of protease inhibitors. Such data would be integral to future evaluation of the impact of diagnostic and therapeutic strategies.

Enteric viruses in HIV-related diarrhoea

HIV-related diarrhoea is an important cause of morbidity and mortality in HIV infection. Cytomegalovirus is a well-established cause of diarrhoea, but the role of other enteric viruses is less clear and will be discussed here. The clinical manifestations, disease mechanisms, diagnostic techniques and current treatments for the management of these infections are reviewed.

Outcome of AIDS-associated cytomegalovirus colitis in the era of potent antiretroviral therapy

The effect of protease inhibitors (PIs) on the outcome of AIDS-associated cytomegalovirus (CMV) colitis is unknown. The aim of this study was to determine the impact of PIs on the recurrence of CMV disease and long-term survival in a large cohort of acquired immunodeficiency syndrome (AIDS) patients with CMV colitis. We reviewed the medical records of 252 AIDS patients who were diagnosed with CMV colitis by colonoscopy between January 1992 and January 1997 at Bellevue Hospital (New York, NY, U.S.A.). Follow-up data were obtained from chart review and direct telephone contact. A complete response to ganciclovir and/or foscarnet therapy was seen in 87.0% of the patients. Recurrence of CMV colitis occurred in 53.1% of patients and was significantly less common in those who received maintenance therapy (36.1% vs. 56.7%; p = 0.03) and in those who were treated with PIs (22.8% vs. 71.9%; p < 0.001). During follow-up. 69.3% of patients died. Multivariate analysis using Cox regression showed that mortality was increased in patients with recurrent CMV colitis (relative risk [RR] of death, 1.7: 95% CI, 1.1-2.6; p = 0.02) and comorbid disease (RR, 1.5: 95% CI, 1.1-2.2; p = 0.02), and decreased in those who were treated with PIs (RR, 0.42; 95% CI, 0.3-0.7; p = 0.001). The median survival was 71 weeks and was significantly longer in patients who were treated with PIs than in those who did not receive these potent anti-retroviral medications (99 vs. 51 weeks; p < 0.001). PIs significantly improve the outcome of AIDS-associated CMV colitis.

Endoscopy in acquired immunodeficiency syndrome patients with diarrhea and negative stool studies

BACKGROUND

Diarrhea is a frequent gastrointestinal symptom in patients with acquired immuno-deficiency syndrome (AIDS) and is a major source of morbidity and mortality. A stepwise diagnostic approach is often recommended to search for treatable causes. However, whether the stepwise diagnostic approach is adequate for planning treatment and whether specific treatment for infectious etiologies will affect the survival of patients with AIDS remain unknown.

METHODS

From March 1996 to September 1997, endoscopy was performed in AIDS patients with diarrhea, the etiology of which was not identified by noninvasive methods. Specific treatment was given according to the identified etiologies and symptomatic treatment was given for those without definite diagnosis. The clinical symptoms, signs, and duration of follow-up were recorded and survival patterns were analyzed.

RESULTS

Etiologic diagnoses were made in 26 of 40 patients (65%) who underwent endoscopic studies. Amebic colitis and cytomegalovirus colitis were the 2 leading causes of prolonged diarrhea in patients with AIDS. Thirty-five patients (87.5%) recovered after treatment. The difference in survival time after diarrhea between patients whose symptoms resolved after treatment and those who continued to have diarrhea was statistically significant (p < 0.001).

CONCLUSIONS

Endoscopic studies were helpful for the diagnosis of prolonged diarrhea in AIDS patients who had negative stool studies and did not respond to 2 weeks of empiric treatment. Specific treatment according to the results of endoscopy may improve survival in these patients.

Impact of protease inhibitors on the outcome of human immunodeficiency virus-infected patients with chronic diarrhea

OBJECTIVE

The effect of protease inhibitors on the outcome of chronic HIV-related diarrhea is unknown. The aim of this study was to compare the response to treatment of chronic HIV-related diarrhea, recurrence of diarrhea, and survival in a large cohort of individuals taking protease inhibitors to the outcome in similar patients not receiving protease inhibitors.

METHODS

We reviewed the medical records of all patients referred between October 1993 and October 1996 at Bellevue Hospital for endoscopic evaluation of chronic HIV-related diarrhea after negative stool examination. Only patients presenting after December 1995 received protease inhibitor therapy. Follow-up data were obtained from chart review and direct telephone contact. The success of antidiarrheal therapy was compared between protease inhibitor and nonprotease inhibitor groups for patients receiving pathogen-specific therapy and for those with no pathogens found on endoscopy.

RESULTS

Two hundred eighty-two of 307 patients evaluated for chronic diarrhea were followed for a mean of 69.9+/-34.1 weeks. Patients receiving protease inhibitors had a significantly higher rate of successful response to antidiarrheal therapy (62.0% vs 33.5%, p < 0.001). Protease inhibitors were associated with a significant decrease in stool frequency (4.8+/-4.5 vs 3.4+/-4.6 bowel movements per day, p = 0.01), an increase in weight (2.4+/-5.9 vs -1.6+/-6.2 kg, p < 0.001), a decrease in recurrence of diarrhea (34.8% vs 15.3%, p = 0.02), and a longer mean survival (148 vs 118 weeks, p = 0.002).

CONCLUSIONS

Protease inhibitors significantly improve the outcome of antidiarrheal therapy and survival in patients with chronic HIV-associated diarrhea.

Infectious Enteritis

Initial management of acute infectious enteritis should focus on fluid and electrolyte repletion and symptomatic care. A decision to prescribe empiric antibiotic therapy should rest on clinical or epidemiologic features of the illness that suggest a treatable bacterial origin or a high-risk host. This decision should be reinforced by the detection of leukocytes or blood in the stool. If empiric therapy is indicated, a quinolone is generally the best initial choice. A stool culture yielding an enteropathogen should generally be specifically treated. A possible exception is uncomplicated Salmonella gastroenteritis in an otherwise healthy host. Nosocomial diarrhea is caused by Clostridium difficile in a minority of cases. Because diagnostic studies for this pathogen are sufficiently sensitive and specific, empiric antibiotic treatment for C. difficile is seldom indicated. Diarrhea in AIDS patients is best worked up and managed in a stepwise fashion, beginning with simple measures. Endoscopy or surgery are seldom indicated in the evaluation and management of infectious enteritis.

Prevalence of enteric pathogens in HIV-related diarrhea in the midwest

HIV disease is often associated with the condition of diarrhea, which may be accompanied by enteric infection or gastrointestinal tumor. This study prospectively investigated 27 episodes of chronic diarrhea in 24 patients with HIV infection. Upper endoscopy and sigmoidoscopy with biopsies at three sites (distal duodenum, sigmoid colon, and rectum) and viral and mycobacterial blood cultures were performed. Stool specimens were sent for standard tests. A primary infectious diagnosis was found in 10 (37%) of 27 episodes: cytomegalovirus (CMV) colitis (n = 4), 3 microsporidiosis (n = 3), cryptosporidiosis (n = 2), and colonic histoplasmosis (n = 1). Patients with CD4 counts of less than 50 cells/mm3 and with lower albumin levels were more likely to have a primary infectious diagnosis. Adenovirus was found in 7 cases but was often associated with another organism; these were not considered to be primary diagnoses. Blood cultures for viruses were not useful, and all mycobacterial cultures were negative. A flexible sigmoidoscopy with histologic examination and culture of biopsy samples were the diagnostic tools that yielded most infectious diagnoses. Follow-up showed that two thirds of patients improved with nonspecific antidiarrheal medications regardless of diagnosis. The study supports a minimalistic approach to the problem of diarrhea in patients with HIV infection. Upper and lower endoscopy lead to a precise diagnosis in a minority of cases, and the outcome was similar in patients with or without a primary infectious diagnosis.

A prospective study of endoscopy in HIV-associated diarrhea

OBJECTIVE

Diarrhea commonly occurs in persons with human immunodeficiency virus (HIV) infection. The optimal use of endoscopic procedures remains poorly studied for patients with HIV-related diarrhea. The purpose of this study is to compare the diagnostic yield of a complete endoscopic work-up including an esophagogastroduodenoscopy and colonoscopy to a more limited approach of biopsies obtainable by flexible sigmoidoscopy.

METHODS

A prospective study of 79 patients with HIV-related diarrhea. Upper endoscopy and colonoscopy were performed with tissue biopsies labelled according to location within the colon or small intestine.

RESULTS

A new infection was diagnosed in 22 of 79 patients (28%). Biopsy of the left colon yielded an enteric pathogen in 17 of 22 patients (sensitivity: 77%) and in 15 of 15 patients with cytomegalovirus colitis (sensitivity: 100%). Combined left and right colonic biopsies had a sensitivity of 82%. Combined colonic and terminal ileum biopsies missed no pathogens. Duodenal biopsies yielded no additional pathogens beyond those identified by colonoscopy and terminal ileal biopsy. Patients with a new pathogen diagnosed had significantly lower CD4 lymphocyte counts as compared to patients without a new pathogen (p = 0.001).

CONCLUSIONS

For patients with CD4 counts < 100/mm3 and unexplained AIDS-related diarrhea, flexible sigmoidoscopy with biopsy is a sufficiently thorough endoscopic evaluation.

Misdiagnosis of specific cytomegalovirus infection of the ileoanal pouch as refractory idiopathic chronic pouchitis: report of two cases

PURPOSE

Chronic nonspecific reservoir ileitis (pouchitis) occurs in 5 to 10 percent of patients who undergo ileal pouch-anal anastomosis for ulcerative colitis. Specific infection of the ileal pouch-anal anastomosis with cytomegalovirus has not been reported.

AIM

We report two patients with specific cytomegalovirus infection of the ileal pouch-anal anastomosis, initially misdiagnosed as idiopathic chronic pouchitis.

CASE SERIES

Patient 1 had ileal pouch-anal anastomosis for ulcerative colitis. Three years later she had diarrhea, fever, pelvic pain, and pouch inflammation at endoscopy consistent with pouchitis. She had no response to medical therapy. Repeat endoscopy showed persistent inflammation and biopsies showed cytomegalovirus. She had symptomatic improvement after treatment with intravenous ganciclovir, 10 mg/kg/day for ten days (stopped for rash). Repeat pouch biopsies were negative for cytomegalovirus. Patient 2 had ileal pouch-anal anastomosis for ulcerative colitis. Nine years later she had resection of obstructing stricture at previous loop ileostomy site. She underwent reoperation with ileostomy and pouch defunctionalization for peritonitis. Four weeks later she had fever and bloody discharge from the diverted pouch. Pouch endoscopy with biopsy showed inflammation consistent with pouchitis. She had no response to medical therapy. Re-examination of pouch biopsies with a specific monoclonal immunofluorescent stain showed cytomegalovirus. She had symptomatic improvement after treatment with intravenous ganciclovir, 10 mg/kg/day for 21 days. Repeat pouch biopsies were negative for cytomegalovirus.

CONCLUSIONS

Specific cytomegalovirus infection of the ileal pouch-anal anastomosis may be misdiagnosed as idiopathic refractory chronic pouchitis. Cytomegalovirus must be excluded before immune modifier therapy or pouch excision in these patients.

Gastrointestinal infections in the immunocompromised host

Gastrointestinal infections are a frequent and important complication of immunodeficiency diseases and immunosuppressive therapy. Such infections may be severe, prolonged, or even fatal, whereas the same infections are typically mild and transient in immunocompetent persons. In this regard, the strong association between HIV-induced immunosuppression and the increased prevalence of severe enteric infections is strong evidence of the link between immune function and defense against enteric pathogens. Because gastrointestinal infections in immunocompromised persons are frequently severe and life-threatening, a vigorous approach to the diagnostic evaluation and therapeutic management is advocated by many clinical investigators. In this review, we summarize the important new developments, particularly during the past year, regarding gastrointestinal infections in immunocompromised persons.

Diagnostic yield and cost-effectiveness of endoscopy in chronic human immunodeficiency virus-related diarrhea

BACKGROUND

Endoscopy is commonly performed in patients with chronic human immunodeficiency virus (HIV)-related diarrhea after negative stool studies. The aim of this study was to determine the diagnostic yield and cost-effectiveness of endoscopy in this setting.

METHODS

Consecutive HIV-infected patients with chronic unexplained diarrhea who were referred for diagnostic endoscopy were identified. Patient charts, pathology reports, and endoscopy records were reviewed.

RESULTS

A total of 479 endoscopic procedures were performed in 307 patients. A pathogen was identified in 147 patients (47.9%); cytomegalovirus was the most frequent organism found (21.5%). The average cost of identifying a pathogen by endoscopy was $3822.94. Colonoscopy had a greater diagnostic yield than flexible sigmoidoscopy (38.7% vs. 22.4%, p = 0.009) and was more cost-effective. The yield of upper endoscopy was 29.6%. In patients with a CD4 count of less than 100/mm3, endoscopy had a higher diagnostic yield (62.8% vs. 8.3%, p < 0.0001) and a lower cost of identifying a pathogen ($2943.92 vs. $21,583.51) than in those with higher CD4 counts.

CONCLUSIONS

Endoscopy frequently identifies a pathogen in HIV-related chronic diarrhea. Colonoscopy is the most cost-effective procedure. Endoscopic evaluation has a significantly higher diagnostic yield and is considerably more cost-effective in patients with a CD4 count of less than 100/mm3 than in those with higher CD4 counts.

Evaluation of diarrhea in HIV-infected patients

Diarrhea is a major problem for patients infected with HIV: initial studies indicated that 50% of HIV-seropositive patients developed diarrhea, but this may be an underestimate. Diarrhea has an appreciable adverse affect on the quality of life of these patients; also, they use more health care facilities and health care dollars than HIV-positive patients without diarrhea. Individuals who have homosexuality or bisexuality as their HIV risk factor are more likely to have diarrhea and to have an enteric pathogen identified as the cause of diarrhea than are patients who have heterosexuality or intravenous drug use as their risk factor.

Comparison of duodenal with jejunal biopsy and aspirate in chronic human immunodeficiency virus-related diarrhea

OBJECTIVES

In human immunodeficiency virus (HIV)-infected patients with chronic unexplained diarrhea, upper endoscopy with small bowel biopsy and aspirate is often performed to identify treatable pathogens. The purpose of this study was to compare the diagnostic yield of duodenal with jejunal biopsy and aspirate.

METHODS

All HIV-infected patients with chronic unexplained diarrhea who were evaluated by upper endoscopy at Bellevue Hospital Center between January 1992 and January 1997 were identified. Data were collected by reviewing patient charts, endoscopy reports, and pathology records.

RESULTS

During the 5-yr study period, 442 patients underwent upper endoscopy with sampling of the duodenum (N=173) or jejunum (N=269). A pathogen was identified in 123 patients (27.8%). Microsporidia was the most common organism detected (12.2%). The diagnostic yield of jejunal biopsy and aspirate was significantly higher than that obtained from the duodenum (32.3% vs 20.8%, p=0.009). Small bowel aspirates detected a pathogen in only 1.8% of patients evaluated, and there was no difference in the yield of duodenal and jejunal aspirates (1.3% vs 2.1%, p=0.7). Patients with a CD4 count of < 100 cells/mm3 were significantly more likely to have a pathogen identified than those with higher CD4 counts (38.8% vs 7.1%,p < 0.0001).

CONCLUSIONS

Upper endoscopy with small bowel biopsy and aspirate identifies a pathogen in 27.8% of individuals with HIV-related chronic unexplained diarrhea. In this patient population, jejunal biopsies acquired by enteroscopy are superior to those obtained from the duodenum. Small bowel aspirates are of little value in the workup of chronic HIV-related diarrhea.

Small intestine pathogens in AIDS: conventional and opportunistic

The small intestine, coming in direct contact with ingested potential pathogens, depends on active mucosal immunity to withstand invasion and damage. In patients with AIDS and severe impairment of immunoregulatory lymphocytes, proliferation of protozoal, viral, bacterial, and fungal pathogens produces diarrhea and malabsorption. When noninvasive tests of stool and blood fail to identify responsible organisms, endoscopy can reveal mucosal lesions which are suggestive if not diagnostic. Cryptosporidium, cf2E. intestinalis, cf1CMV, MAC, and other infections can be identified by intestinal biopsy quicker and often at lower overall cost than they can be by culture.

Cytomegalovirus colitis in acquired immunodeficiency syndrome: a clinical and endoscopic study

BACKGROUND

Cytomegalovirus colitis is an important complication of the acquired immunodeficiency syndrome (AIDS), although the clinical and colonoscopic manifestations of this disease have not been systematically characterized.

METHODS

Patients with AIDS and cytomegalovirus colitis were prospectively identified at two medical centers. The diagnosis of cytomegalovirus disease was based on established endoscopic and histologic criteria. At the time of sigmoidoscopic and/or colonoscopic examination, clinical features were recorded; the location, size, and appearance of all endoscopic abnormalities were documented; and multiple biopsies of any lesions were performed.

RESULTS

Fifty-six patients were studied. The majority of the patients were homosexual men with severe immunodeficiency (median CD4 lymphocyte count 15/mm3, range 1 to 294/mm3). Chronic diarrhea and abdominal pain were the most frequent clinical manifestations, seen in 45 (80%) and 28 (50%) patients, respectively. Five patients (9%) presented with lower gastrointestinal hemorrhage, three of whom had no antecedent history of diarrhea. The colonoscopic abnormalities could be categorized into three main groups: colitis associated with ulcer (39%), ulceration alone (38%), or colitis alone (20%). Subepithelial hemorrhage was a prominent endoscopic manifestation of disease. Of the 31 patients undergoing colonoscopy to the cecum, in four (13%) endoscopic evidence of disease was limited to the colon proximal to the splenic flexure.

CONCLUSIONS

Cytomegalovirus colitis in AIDS appears to have variable but stereotypical clinical and colonoscopic manifestations. Distal colitis associated with ulceration is the most common colonoscopic pattern.

Endoscopic evaluation of chronic human immunodeficiency virus-related diarrhea: is colonoscopy superior to flexible sigmoidoscopy?

OBJECTIVES

In patients with chronic human immunodeficiency virus (HIV)-related diarrhea undergoing lower endoscopy, the decision to perform flexible sigmoidoscopy or colonoscopy is controversial. The purpose of this study is twofold: 1) to evaluate the diagnostic yield of colonoscopy in a large group of patients with chronic HIV-related diarrhea and negative stool studies, and 2) to determine whether colonoscopy is superior to flexible sigmoidoscopy in this setting.

METHODS

All HIV-infected patients with chronic diarrhea who were referred for diagnostic colonoscopy at Bellevue Hospital Center between January 1992 and December 1996 were identified. Patient charts, pathology reports, and endoscopy records were reviewed.

RESULTS

During the 5-yr study period, 317 consecutive patients with chronic unexplained diarrhea undergoing colonoscopy were identified. A potential cause of diarrhea was found in 116 patients (36.6%). Cytomegalovirus was the most common pathogen detected (24%). The yield of colonoscopy was significantly higher in patients with a CD4 count of <100 cells/mm3 than in those with higher CD4 counts (44.8% vs 6.4%, p < 0.0001). Thirty percent of pathogens and 75% of lymphomas were identified only on biopsies taken from the proximal colon, well beyond the reach of the flexible sigmoidoscope. Importantly, 94% of the pathogens that were found only in the proximal colon were organisms for which effective therapy is currently available.

CONCLUSIONS

Colonoscopy is superior to flexible sigmoidoscopy in HIV-infected patients with chronic unexplained diarrhea. If flexible sigmoidoscopy had been performed instead of colonoscopy, 30% of pathogens would have been missed and 75% of lymphomas would have escaped detection.

Gastrointestinal pathology in HIV-infected patients

Specific pathologic processes, particularly oral, esophageal, and intestinal infections, are common in the alimentary tract of AIDS patients. Many of these diseases are adequately assessed only by biopsy with histologic examination. Most are rare or unreported in immunocompetent hosts and are easily missed by those not familiar with them. This article describes the gross or endoscopic and histologic appearances and the diagnostic criteria for enteric pathologic processes seen in HIV-infected individuals.

Diarrheal diseases associated with HIV infection

Diarrhea is a major complication of HIV infection and adversely impacts health care costs, quality of life, and even survival of patients. There is a wide variety of potential causes of diarrhea in HIV-infected patients, and the number of pathogens found continues to increase with time. In addition, there is some controversy concerning the role of some organisms in the pathogenesis of diarrhea and the appropriate diagnostic evaluation of affected patients. This article reviews our current understanding of these pathogens and some of the diagnostic and therapeutic approaches for diarrhea associated with HIV infection.

Oxides, onions, and other matters gastrointestinal--1996--a perspective

A selection of landmark articles for a given year in any subject risks being somewhat subjective, and subjectivity is best avoided in scientific endeavor. However, the very nature of such a selection process invites judgment. Like most judges, I, too, claim to avoid conscious bias, but no one who has ever graced the bench can claim that at the subconscious level personal bias has never crept into a decision. Similarly, deep down in the vault of my subconscious, I love a maverick. That perhaps explains why so many articles that challenge long-held beliefs have especially found favor. Among them are those that question the strength of the association of Helicobacter pylori with gastric cancer, the usefulness of surveillance endoscopy in patients with Barrett's esophagus, a randomized trial that casts doubt on the preeminence of laparoscopic cholecystectomy, and a metaanalysis that concludes that corticosteroids may not be nearly as good for alcoholic hepatitis as we were once told. I have tried to resist the temptation to be too laudatory of technologic advancement, unless the benefit to the patient of such technology has been defined clearly. Thus, of all of the new technologies (endoscopic retrograde choledochopancreatography is no longer a new technology), only endoscopic ultrasonography finds a place. Articles that assess preventive strategies and are in the realm of epidemiology have received mention. All in all, 1996 was not a spectacular year for major therapeutic advances. In contrast, some notable advances have been made in the laboratory, and perhaps the most important has to do with the role of nitric oxide both in the regulation of normal function and in the genesis of disease.

Agents of diarrhea

Diarrhea is a common problem for AIDS patients, and is chronic and debilitating. A thorough evaluation will reveal a pathogen in the majority of patients, and the organisms most frequently identified in AIDS patients with chronic diarrhea are Cryptosporidium, microsporidia, and Mycobacterium avium complex. Bacterial pathogens are more common in AIDS patients than in the general population and may present in different ways from infections in immunocompetent hosts. Other pathogens, including Cryptosporidium and microsporidia, are difficult to diagnose and have no effective therapy. Moreover, enteric viruses and HIV itself may contribute to the diarrhea. In addition to microbes, other factors such as medication, immune dysregulation, automatic dysfunction, and nutritional supplementation play a substantial role in diarrhea of AIDS patients.

Gastrointestinal and nutritional sequelae of bone marrow transplantation

The nature of the gastrointestinal injury following bone marrow transplantation and its clinical and nutritional sequelae are poorly defined. Prospective assessments of gastrointestinal function, nutritional status, and wellbeing were therefore carried out in 47 consecutive patients (28 males, 19 females; mean age 8.4 years) undergoing bone marrow transplant. 31 diarrhoeal episodes (median duration 9.5 days) occurred in 27 patients at a median of 10 days after transplantation. Ninety one per cent of episodes were associated with protein losing enteropathy. Protein losing enteropathy was more severe in graft-versus-host disease (GVHD) comparing with other causes. It led to a substantial fall in serum albumin and there was a negative correlation between faecal alpha 1-antitrypsin concentrations and serum albumin. Transient pancreatic insufficiency developed in 18 patients, and pancreatitis in one. Intestinal permeability was normal in 12 patients who had no diarrhoea during the conditioning treatments. Diarrhoeal patients had a significantly greater decrease in nutritional status and wellbeing than patients without diarrhoea. Gastrointestinal injury following bone marrow transplantation is thus complex. Severe protein losing enteropathy in this context suggests the presence of GVHD.