Bio

Professional Education


  • Internal Medicine Specialist, Universidad de Chile, Internal Medicine (2010)
  • Doctor of Medicine, Universidad de Chile, Medicine (2007)
  • Bachelor of Medicine, Universidad de Chile, Medicine (2005)
  • Master of Science, Stanford University, EPIDM-MS (2013)

Publications

Journal Articles


  • Recurrent Hepatocellular Carcinoma and Poorer Overall Survival in Patients Undergoing Left-sided Compared With Right-sided Partial Hepatectomy. Journal of clinical gastroenterology Valenzuela, A., Ha, N. B., Gallo, A., Bonham, C., Ahmed, A., Melcher, M., Kim, L. H., Esquivel, C., Concepcion, W., Ayoub, W. S., Lutchman, G. A., Daugherty, T., Nguyen, M. H. 2015; 49 (2): 158-164

    Abstract

    We aimed to determine the incidence and predictors of recurrent hepatocellular carcinoma (HCC) after partial hepatectomy.Liver transplantation is the preferred treatment for selected patients with HCC, but access to donor organs is limited. Partial hepatectomy is another accepted treatment option; however, postoperative recurrence is frequently observed.This is a retrospective cohort study of 107 consecutive patients who underwent partial hepatectomy for HCC between January 1993 and February 2011 at a US University Medical Center. Study endpoints were recurrent HCC, death, loss to follow-up, or last visit without HCC.The study cohort was 78% male with a median age of 61 years and 59% Asians. A total of 50 patients developed recurrent HCC (46.7%) after a median follow-up of 12 (1 to 69) months postresection. Recurrent HCC was significantly higher in patients with left-sided resection (41% at year 1, 54% at year 2, 62% at year 3, 81% at year 4, and 90% at year 5) compared with right-sided resection (18% at year 1, 34% at year 2, 36% at year 3, 44% at year 4, and 72% at year 5). In multivariate Cox proportional hazards model also inclusive of anatomic resection and TNM stage 3/4, left-sided resection was significantly associated with increased HCC recurrence (hazard ratio, 2.13; P=0.02; 95% confidence interval, 1.08-4.2) compared with right-sided resection.HCC recurrence rate is higher among those undergoing left-sided resection: 54% at year 2 and 81% at year 4. Liver transplantation should be considered in patients who are at high risk for recurrence.

    View details for DOI 10.1097/MCG.0000000000000144

    View details for PubMedID 24804988

  • Identification of clinical features and autoantibodies associated with calcinosis in dermatomyositis. JAMA dermatology Valenzuela, A., Chung, L., Casciola-Rosen, L., Fiorentino, D. 2014; 150 (7): 724-729

    Abstract

    Prior studies have estimated that up to 20% of adults with dermatomyositis (DM) have calcinosis, which can lead to significant morbidity. Identification of risk factors may provide a better understanding of the pathogenesis and ultimately therapy for this difficult clinical problem. Risk factors for calcinosis in adults with DM have not been extensively studied.To determine the prevalence of calcinosis and to identify associated clinical features in a cohort of extensively phenotyped adults with DM.A cross-sectional study of 126 patients diagnosed as having DM from January 1, 2006, through January 1, 2013, was performed. Patients were adults (≥18 years of age) attending the Stanford University Medical Center clinic.Calcinosis, defined as the presence of calcium deposition in the skin and subcutaneous tissues on physical examination.Fourteen patients (11.1%) had calcinosis, with the extremities most commonly involved. Patients with vs those without calcinosis had a longer disease duration (median, 6.9 years; range, 2.4-18.1; vs median, 3.9 years; range, 0.2-19.2 years; P = .003) and more fingertip ulcers (50.0% vs 9.3%, P < .001). An association between calcinosis and both interstitial lung disease and anti-MDA-5 autoantibodies was identified, but this association did not persist in multivariate models that adjusted for fingertip ulcers. Fingertip ulcers and disease duration were strongly associated with calcinosis in all multivariate models, independent of the underlying autoantibody present. Autoantibodies to NXP-2 were associated with calcinosis (odds ratio, 15.52; 95% CI, 2.01-119.90), whereas anti-transcriptional intermediary factor 1-γ antibodies were protective (odds ratio, 0.2; 95% CI, 0.01-0.99) in multivariate analyses that adjusted for fingertip ulcers and other covariates.Calcinosis was a relatively uncommon clinical feature in our cohort of adults with DM. Our data suggest that calcinosis is positively associated with longer disease duration, fingertip ulcers, and NXP-2 autoantibodies and negatively associated with transcriptional intermediary factor 1-γ antibodies. A common vascular mechanism may underlie the development of both calcinosis and fingertip ulcers in patients with DM.

    View details for DOI 10.1001/jamadermatol.2013.10416

    View details for PubMedID 24869801

  • Primary Surgical Resection Versus Liver Transplantation for Transplant-Eligible Hepatocellular Carcinoma Patients DIGESTIVE DISEASES AND SCIENCES Wong, R. J., Wantuck, J., Valenzuela, A., Ahmed, A., Bonham, C., Gallo, A., Melcher, M. L., Lutchman, G., Concepcion, W., Esquivel, C., Garcia, G., Daugherty, T., Nguyen, M. H. 2014; 59 (1): 183-191

    Abstract

    Hepatocellular carcinoma (HCC) is a leading cause of mortality worldwide. Existing studies comparing outcomes after liver transplantation (LT) versus surgical resection among transplant-eligible patients are conflicting.The purpose of this study was to compare long-term survival between consecutive transplant-eligible HCC patients treated with resection versus LT.The present retrospective matched case cohort study compares long-term survival outcomes between consecutive transplant-eligible HCC patients treated with resection versus LT using intention-to-treat (ITT) and as-treated models. Resection patients were matched to LT patients by age, sex, and etiology of HCC in a 1:2 ratio.The study included 171 patients (57 resection and 114 LT). Resection patients had greater post-treatment tumor recurrence (43.9 vs. 12.9 %, p < 0.001) compared to LT patients. In the as-treated model of the pre-model for end stage liver disease (MELD) era, LT patients had significantly better 5-year survival compared to resection patients (100 vs. 69.5 %, p = 0.04), but no difference was seen in the ITT model. In the multivariate Cox proportional hazards model, inclusive of age, sex, ethnicity, tumor stage, and MELD era (pre-MELD vs. post-MELD), treatment with resection was an independent predictor of poorer survival (HR 2.72; 95 % CI, 1.08-6.86).Transplant-eligible HCC patients who received LT had significantly better survival than those treated with resection, suggesting that patients who can successfully remain on LT listing and actually undergo LT have better outcomes.

    View details for DOI 10.1007/s10620-013-2947-8

    View details for Web of Science ID 000330585500029

  • Validation of a Novel Radiographic Scoring System for Calcinosis Affecting the Hands of Patients with Systemic Sclerosis. Arthritis care & research Chung, L., Valenzuela, A., Fiorentino, D., Stevens, K., Li, S., Harris, J., Hutchinson, C., Assassi, S., Beretta, L., Lakshminarayanan, S., Rodriguez-Reyna, T. S., Denton, C. P., Taillefer, R. G., Herrick, A. L., Baron, M. 2014

    Abstract

    Objective: There are currently no validated outcome measures to assess calcinosis severity in systemic sclerosis (SSc). We sought to develop and validate a novel radiographic scoring system for calcinosis affecting the hands of SSc patients for potential use in future clinical trials. Methods: Following a 1-hour teleconference training session, 12 investigators (8 rheumatologists, 1 dermatologist, 3 radiologists) scored 12 hand radiographs in random order using two scoring systems (termed "simple" and "complex"), and re-scored 2 randomly assigned radiographs after a minimum of 24 hours. Inter-rater and intra-rater reliability were assessed using a weighted kappa coefficient for the simple system, and intraclass correlation coefficient (ICC) for the complex system (ICC < 0.4 poor, 0.4-0.7 moderate, > 0.7 excellent). Results: Mean time to complete the complex scoring system was significantly longer than the simple scoring system (4.0 vs. 0.4 minutes, p<.0001). Overall inter-rater reliability for the simple scoring system was poor (kappa=0.39, 95% CI 0.1-0.52), but improved if dichotomized as mild/moderate vs. severe (kappa=0.51, 95% CI 0.26-0.7). Inter-rater reliability was excellent for the complex scoring system (ICC=0.89, 95% CI 0.86-0.92). Intra-rater reliability was moderate for the simple scoring system (kappa=0.67, 95% CI 0.37-0.96), but almost perfect for the complex scoring system (ICC=0.93, 95%CI 0.89-0.97). Conclusion: We developed a novel radiographic scoring system that accounts for the area coverage, density, and anatomic location of calcinosis affecting the hands in patients with SSc. This scoring system is feasible with excellent reliability and should undergo further validation testing for use in clinical trials. © 2014 American College of Rheumatology.

    View details for DOI 10.1002/acr.22434

    View details for PubMedID 25155948

  • Incidence of Hepatocellular Carcinoma Among US Patients With Cirrhosis of Viral or Nonviral Etiologies CLINICAL GASTROENTEROLOGY AND HEPATOLOGY Mair, R. D., Valenzuela, A., Ha, N. B., Ayoub, W. S., Daugherty, T., Lutchman, G. A., Garcia, G., Ahmed, A., Nguyen, M. H. 2012; 10 (12): 1412-1417

    Abstract

    We aimed to identify risk factors for hepatocellular carcinoma (HCC) in patients with cirrhosis in the United States. We performed a prospective study to identify associations between etiologies of cirrhosis and ethnicity with HCC incidence.We used convenience sampling to select a cohort of 379 patients with cirrhosis who visited the liver clinic at the Stanford University Medical Center from 2001 to 2009 (65% male, 75% white or Hispanic, and 20% Asian). Study end points were HCC diagnosis by histology or noninvasive criteria, liver transplantation, or last screening without HCC. Patients were followed up, with ultrasound or computed tomographic imaging analyses and measurements of serum levels of ?-fetoprotein, approximately every 6 months, for a median time of 34 months (range, 6-99 mo).The etiologies of cirrhosis in the cohort were 68% hepatitis C, 7% hepatitis B, and 25% nonviral. Forty-four patients (12%) were diagnosed with HCC during the follow-up period. Patients with cirrhosis related to viral hepatitis had a statistically significantly higher incidence of HCC than those with nonviral diseases in Kaplan-Meier analysis (P = .04). There was no statistically significant difference in HCC incidence between Asian and non-Asian patients. In a multivariate Cox proportional hazards model that included age, sex, ethnicity, etiology, and Child-Pugh-Turcotte score, viral cirrhosis was associated significantly with HCC, compared with nonviral cirrhosis (hazard ratio, 3.6; 95% confidence interval, 1.3-10.1; P = .02) but Asian ethnicity was not.In a diverse cohort of patients in the United States with cirrhosis, a viral etiology of cirrhosis was associated with increased incidence of HCC, but Asian ethnicity was not. These findings indicate the importance of cirrhosis etiology in determining risk for HCC.

    View details for DOI 10.1016/j.cgh.2012.08.011

    View details for Web of Science ID 000312265900021

    View details for PubMedID 22902757

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