Douglas L. Nguyen
University of California, Irvine
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Featured researches published by Douglas L. Nguyen.
Therapeutic Advances in Gastroenterology | 2015
Douglas L. Nguyen; Lena B. Palmer; Emily T. Nguyen; Stephen A. McClave; Robert G. Martindale; Matthew L. Bechtold
Objectives: Many patients with Crohn’s disease on infliximab maintenance therapy have recurrent symptoms despite an initial clinical response. Therefore, concomitant therapies have been studied. We conducted a meta-analysis to assess the effect of specialized enteral nutrition therapy with infliximab versus infliximab monotherapy in patients with Crohn’s disease. Methods: A comprehensive search of multiple databases was performed. All studies of adult patients with Crohn’s disease comparing specialized enteral nutrition therapy (elemental or polymeric diet with low-fat or regular diet) with infliximab versus infliximab monotherapy without dietary restrictions were included. Meta-analysis was performed using the Mantel–Haenszel (fixed effect) model with odds ratio (OR) to assess for clinical remission. Results: Four studies (n = 342) met inclusion criteria. Specialized enteral nutrition therapy with infliximab resulted in 109 of 157 (69.4%) patients reaching clinical remission compared with 84 of 185 (45.4%) with infliximab monotherapy [OR 2.73; 95% confidence interval (CI): 1.73–4.31, p < 0.01]. Similarly, 79 of 106 (74.5%) patients receiving enteral nutrition therapy and infliximab remained in clinical remission after one year compared with 62 of 126 (49.2%) patients receiving infliximab monotherapy (OR 2.93; 95% CI: 1.66–5.17, p < 0.01). No publication bias or heterogeneity was noted for either outcome. Conclusions: The use of specialized enteral nutrition therapy in combination with infliximab appears to be more effective at inducing and maintaining clinical remission among patients with Crohn’s disease than infliximab monotherapy.
Current Gastroenterology Reports | 2016
Matthew R. Kappus; Mardeli Saire Mendoza; Douglas L. Nguyen; Valentina Medici; Stephen A. McClave
Sarcopenia, a loss of muscle mass, is being increasingly recognized to have a deleterious effect on outcomes in patients with chronic liver disease. Factors related to diet and the inflammatory nature of chronic liver disease contribute to the occurrence of sarcopenia in these patients. Sarcopenia adversely influences quality of life, performance, morbidity, success of transplantation, and even mortality. Specific deficiencies in macronutrients (protein, polyunsaturated fatty acids) and micronutrients (vitamins C, D, and E, carotenoids, and selenium) have been linked to sarcopenia. Lessons learned from nutritional therapy in geriatric patient populations may provide strategies to manage sarcopenia in patients with liver disease. Combining diet modification and nutrient supplementation with an organized program of exercise may help ameliorate or even reverse the effects of sarcopenia on an already complex disease process.
Gastrointestinal Endoscopy | 2016
Douglas L. Nguyen; M. Mazen Jamal; Emily T. Nguyen; Srinivas R. Puli; Matthew L. Bechtold
BACKGROUND AND AIMSnColonoscopy is extremely important for the identification and removal of precancerous polyps. Bowel preparation before colonoscopy is essential for adequate visualization. Traditionally, patients have been instructed to consume only clear liquids the day before a colonoscopy. However, recent studies have suggested using a low-residue diet, with varying results. We evaluated the outcomes of patients undergoing colonoscopy who consumed a clear liquid diet (CLD) versus low-residue diet (LRD) on the day before colonoscopy by a meta-analysis.nnnMETHODSnScopus, PubMed/MEDLINE, Cochrane databases, and CINAHL were searched (February 2015). Studies involving adult patients undergoing colonoscopy examination and comparing LRD with CLD on the day before colonoscopy were included. The analysis was conducted by using the Mantel-Haenszel or DerSimonian and Laird models with the odds ratio (OR) to assess adequate bowel preparations, tolerability, willingness to repeat diet and preparation, and adverse effects.nnnRESULTSnNine studies (1686 patients) were included. Patients consuming an LRD compared with a CLD demonstrated significantly higher odds of tolerability (OR 1.92; 95% CI, 1.36-2.70; P < .01) and willingness to repeat preparation (OR 1.86; 95% CI, 1.34-2.59; P < .01) with no differences in adequate bowel preparations (OR 1.21; 95% CI, 0.64-2.28; P = .58) or adverse effects (OR 0.88; 95% CI, 0.58-1.35; P = .57).nnnCONCLUSIONnAn LRD before colonoscopy resulted in improved tolerability by patients and willingness to repeat preparation with no differences in preparation quality and adverse effects.
Nutrition in Clinical Practice | 2014
Matthew L. Bechtold; Douglas L. Nguyen; Lena B. Palmer; Laszlo N. Kiraly; Robert G. Martindale; Stephen A. McClave
BACKGROUNDnNasoenteric feeding tubes may easily become dislodged due to patient mental status, transfers, or positional changes. Nasal bridles were introduced to provide a better, more reliable system to secure these tubes. This meta-analysis was performed to evaluate the effectiveness of nasal bridles compared with the traditional method of adhesive tape alone in securing enteral feeding tubes.nnnMATERIALS AND METHODSnMultiple databases were searched (October 2013). All studies that evaluated the use of nasal bridles in adult patients were included in the analysis. Meta-analysis for the outcomes from use of a nasal bridle vs the more traditional method of adhesive tape alone for securing nasoenteric tubes was analyzed by calculating pooled estimates of dislodgement, skin complications, and sinusitis. Statistical analysis was performed using RevMan 5.1.nnnRESULTSnSix studies (n = 594) met the inclusion criteria. Use of a nasal bridle for securing enteral tubes resulted in a statistically significant reduction in tube dislodgement compared with traditional adhesive tape alone (odds ratio [OR], 0.16; 95% confidence interval [CI], 0.10–0.27; P < .01). The use of nasal bridles was associated with a higher rate of skin complications compared with traditional adhesive tape (OR, 4.27; 95% CI, 1.79–10.23; P < .01). Incidence of sinusitis was no different between the 2 groups (OR, 0.26; 95% CI, 0.03–2.28; P = .22).nnnCONCLUSIONnNasal bridles appear to be more effective at securing nasoenteric tubes and preventing dislodgement than traditional use of tape alone.
Therapeutic Advances in Chronic Disease | 2015
Douglas L. Nguyen; Sarah L. Flores; Kareem Sassi; Matthew L. Bechtold; Emily T. Nguyen; Nimisha K. Parekh
Since the approval of the first anti-tumor necrosis factor (anti-TNF) therapy in late 1998, the treatment for Crohn’s disease (CD) has been revolutionized. Anti-TNF therapy has been consistently shown in numerous clinical trials to be effective for patients with more aggressive perianal, internal penetrating, and fistulizing CD. However, the loss of clinical remission is frequent and only one-third of patients remain in clinical remission at 1 year. The pharmacokinetics of anti-TNF is highly variable among patients and could be influenced by many factors including serum albumin, gender, body weight, systemic inflammation and route of administration. The main factor impacting anti-TNF pharmacokinetics and efficacy is the development of immunogenicity where antidrug antibodies accelerate anti-TNF drug clearance. In this review paper, we evaluate the role of combination therapy with anti-TNF drugs and immunomodulators, the role of therapeutic drug monitoring, and strategies to recapture loss of clinical response in order to improve both short- and long-term outcomes in CD patients.
Current Gastroenterology Reports | 2016
Douglas L. Nguyen; Berkeley N. Limketkai; Valentina Medici; Mardeli Saire Mendoza; Lena B. Palmer; Matthew L. Bechtold
Inflammatory bowel disease (IBD) is a group of chronic, lifelong, and relapsing illnesses, such as ulcerative colitis and Crohn’s disease, which involve the gastrointestinal tract. There is no cure for these diseases, but combined pharmacological and nutritional therapy can induce remission and maintain clinical remission. Malnutrition and nutritional deficiencies among IBD patients result in poor clinical outcomes such as growth failure, reduced response to pharmacotherapy, increased risk for sepsis, and mortality. The aim of this review is to highlight the consequences of malnutrition in the management of IBD and describe nutritional interventions to facilitate induction of remission as well as maintenance; we will also discuss alternative delivery methods to improve nutritional status preoperatively.
Hepatology International | 2014
Douglas L. Nguyen; Timothy R. Morgan
Since the late nineteenth century, protein restriction has been shown to improve hepatic encephalopathy. However, malnutrition has been described in up to 60xa0% of cirrhotic patients and is associated with increased mortality. Furthermore, emerging clinical evidence has revealed that a large proportion of cirrhotic patients may tolerate normal protein intake. However, approximately one third of cirrhotic patients with hepatic encephalopathy may need a short course of protein restriction, in addition to maximum medical therapy, to ameliorate the clinical course of their hepatic encephalopathy. For patients with chronic hepatic encephalopathy who are protein-sensitive, modifying their sources of nitrogen by using more vegetable protein, less animal protein, and branched-chain amino acids may improve their encephalopathy without further loss of lean body mass. In conclusion, among cirrhotics with hepatic encephalopathy, modulation of normal protein intake must take into account the patient’s hepatic reserve, severity of hepatic encephalopathy, and current nutritional status.
Current Gastroenterology Reports | 2014
Matthew L. Bechtold; Stephen A. McClave; Lena B. Palmer; Douglas L. Nguyen; Lindsay M. Urben; Robert G. Martindale; Ryan T. Hurt
Short bowel syndrome (SBS) is a manifestation of massive resection of the intestines resulting in severe fluid, electrolyte, and vitamin/mineral deficiencies. Diet and parenteral nutrition play a large role in the management of SBS; however, pharmacologic options are becoming more readily available. These pharmacologic agents focus on reducing secretions and stimulating intestinal adaptation. The choice of medication is highly dependent on the patient’s symptoms, remaining anatomy, and risk versus benefit profile for each agent. This article focuses on common and novel pharmacologic medications used in SBS, including expert advice on their indications and use.
Annals of Gastroenterology | 2016
Matthew L. Bechtold; Fazia Mir; Srinivas R. Puli; Douglas L. Nguyen
Colonoscopy is an important screening and therapeutic modality for colorectal cancer. Unlike other screening tests, colonoscopy is dependent on pre-procedure bowel preparation. If the bowel preparation is poor, significant pathology may be missed. Many factors are known to improve bowel preparation. This review will highlight those factors that may optimize the bowel preparation, including choice of bowel preparation, grading or scoring of the bowel preparation, special factors that influence preparation, and diet prior to colonoscopy that affects bowel preparation. The aim of the review is to offer suggestions and guide endoscopists on how to optimize the bowel preparation for the patients undergoing colonoscopy.
Digestive Diseases and Sciences | 2015
Douglas L. Nguyen; Emily T. Nguyen; Matthew L. Bechtold
BackgroundSeveral studies have evaluated the effect of immunosuppressive therapy for the treatment of inflammatory bowel disease (IBD) on response to routine vaccinations. The overall effect of specific classes of medications (i.e., immunomodulator vs. biologics) on vaccine response remains undefined. The aim of this study was to determine the effect of each class of immunosuppressive therapy in IBD patients on response to routine vaccinations.MethodsA comprehensive search of PubMed/MEDLINE, Scopus, CINAHL, and Cochrane databases was performed (December 2014). All studies on adults comparing vaccine response among IBD patients on immunosuppression with non-immunosuppressed patients were included. Meta-analysis was performed using the Mantel–Haenszel (fixed effects) model with odds ratio (OR) to assess for adequate vaccine response.ResultsIn the pooled analysis of nine studies (Nxa0=xa01474), we found that there was nearly a 60xa0% lower chance of achieving adequate seroprotection in the group that received immunosuppressive therapy compared to the group that was not on any immunosuppressive therapies (OR 0.41 95xa0% CI 0.30, 0.55, pxa0<xa00.001). Specifically, we also demonstrated that patients on immunomodulator monotherapy had a twofold higher probability of achieving adequate immune response to vaccination, compared to patients on anti-tumor necrosis factor (anti-TNF) monotherapy (OR 1.92 95xa0% CI 1.30, 2.84).ConclusionIn conclusion, IBD patients on immunosuppressive therapy have a significantly lower response to routine vaccinations. The greatest effect is seen among patients on anti-TNF and combination immunosuppressive therapy. Routine monitoring of vaccine titers post-vaccination is important to ensure that adequate immunologic response has been achieved among IBD patients.