Vahakn Shahinian

University of Michigan, Ann Arbor, MI, USA

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Publications (6)16.74 Total impact

  • Article: Timing of androgen deprivation therapy use and fracture risk among elderly men with prostate cancer in the United States.
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    ABSTRACT: Fractures are a recognized consequence of androgen deprivation therapy (ADT); however, less is known about the incidence of fracture in relation to the timing of ADT use or the impact of fracture on mortality in men with prostate cancer. Using data from the Surveillance, Epidemiology, and End Results-Medicare linked database, we estimated adjusted hazard ratios (aHRs) using time-dependent Cox regression for fracture incidence related to the recency of exposure and dose among prostate cancer patients on gonadotropin-releasing hormone (GnRH) agonists, as well as mortality associated with fractures. In our cohort of 80 844 patients, ADT was associated with an increased rate of fracture in both non-metastatic patients (aHR = 1.34; 95% confidence interval [CI] = 1.29-1.39) and metastatic patients (aHR = 1.51; 95%CI = 1.36-1.67). Fracture rates increased with increasing cumulative GnRH dose but decreased with increasing number of months since last use in each dose category. The mortality rate doubled for men experiencing a fracture after their diagnosis compared with that for men who did not experience a fracture (aHR = 2.05; 95%CI = 1.98-2.12). ADT in elderly men with prostate cancer increased the incidence of fractures, and the effect appears to diminish with increasing time since the last dose of a GnRH agonist. Experiencing a fracture after the diagnosis of prostate cancer was associated with decreased survival.
    Pharmacoepidemiology and Drug Safety 11/2011; 21(1):70-8. · 2.53 Impact Factor
  • Article: Tackling overtreatment of prostate cancer : The role of comorbidity.
    Jennifer Beebe-Dimmer, Vahakn Shahinian
    Cancer 04/2011; 117(20):4576-8. · 4.77 Impact Factor
  • Article: Androgen deprivation therapy and cataract incidence among elderly prostate cancer patients in the United States.
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    ABSTRACT: The side-effects associated with androgen deprivation therapy (ADT) include weight gain, dyslipidemia, and insulin resistance. As cataracts have been linked to these metabolic abnormalities, an increased risk of cataract may be another adverse consequence of ADT use. Using data from the Surveillance, Epidemiology and End Results-Medicare database, we estimated risk of cataract associated with ADT among 65,852 prostate-cancer patients. ADT treatment was defined as at least one dose of a gonadotropin-releasing hormone agonist or orchiectomy within 6 months after prostate cancer diagnosis. The outcome measure was a first claim of cataract diagnosis identified in Medicare claim files. Cox regression was used to estimate hazard ratios (HR) for the effects of ADT treatment, controlling for confounders. Gonadotropin-releasing hormone agonist use was associated with a modest increase in cataract incidence (HR 1.09, 95% confidence interval 1.06-1.12). Orchiectomy was also associated with an increased risk of cataract among men with no history of cataract prior to prostate cancer diagnosis (HR 1.26, 95% confidence interval 1.07-1.47). In the first systematic investigation of the association between ADT and cataract, our results suggest an elevation in the incidence of cataract among ADT users. Further study, preferably prospective in design, is needed to provide additional evidence to support or refute these findings.
    Annals of epidemiology 03/2011; 21(3):156-63. · 2.95 Impact Factor
  • Article: CKD: a pandemic calling for concerted public health action.
    Rajiv Saran, Vahakn Shahinian
    Advances in chronic kidney disease 05/2010; 17(3):213-4. · 2.42 Impact Factor
  • Article: Surveillance of chronic kidney disease around the world: tracking and reining in a global problem.
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    ABSTRACT: In recent years, there has been a general recognition of the importance of tackling noncommunicable chronic diseases throughout the world and not just in developed nations. Chronic kidney disease (CKD) is increasingly recognized as a public health threat, based on its high prevalence, rising incidence, associated complications, and cost. It is imperative that nations develop screening and surveillance programs related to CKD. This article provides a global perspective on existing and emerging CKD surveillance efforts. A variety of programs are described, ranging from cross-sectional screening studies to determine CKD prevalence; targeted screening of high-risk populations presenting for voluntary testing; to more systematic surveillance within the scope of integrated health care systems in many developed nations. The choice of surveillance programs for many countries will depend on available resources and competing health care priorities. Integration with surveillance programs for other major chronic diseases such as diabetes, hypertension, and obesity is highly desirable and could be a key to the prevention of CKD. Finally, we propose the model of integrated health systems as one that is perhaps best suited to systematic, longitudinal surveillance of many chronic diseases, a model based on a national electronic health care record with linkage across primary care and hospital-based programs. Robust health education efforts and timely dissemination strategies will remain the key to the success of disease surveillance. It is gratifying to note that more and more countries are developing and adopting CKD surveillance programs as part of national disease prevention strategies.
    Advances in chronic kidney disease 05/2010; 17(3):271-81. · 2.42 Impact Factor
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    Article: Gonadotropin-releasing hormone agonist use in men without a cancer registry diagnosis of prostate cancer.
    Yong-fang Kuo, James S Goodwin, Vahakn B Shahinian
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    ABSTRACT: Use of gonadotropin-releasing hormone (GnRH) agonists has become popular for virtually all stages of prostate cancer. We hypothesized that some men receive these agents after only a limited work-up for their cancer. Such cases may be missed by tumor registries, leading to underestimates of the total extent of GnRH agonist use. We used linked Surveillance, Epidemiology and End-Results (SEER)-Medicare data from 1993 through 2001 to identify GnRH agonist use in men with either a diagnosis of prostate cancer registered in SEER, or with a diagnosis of prostate cancer based only on Medicare claims (from the 5% control sample of Medicare beneficiaries residing in SEER areas without a registered diagnosis of cancer). The proportion of incident GnRH agonist users without a registry diagnosis of prostate cancer was calculated. Factors associated with lack of a registry diagnosis were examined in multivariable analyses. Of incident GnRH agonist users, 8.9% had no diagnosis of prostate cancer registered in SEER. In a multivariable logistic regression model, lack of a registry diagnosis of prostate cancer in GnRH agonist users was significantly more likely with increasing comorbidity, whereas it was less likely in men who had undergone either inpatient admission or procedures such as radical prostatectomy, prostate biopsy, or transurethral resection of the prostate. Reliance solely on tumor registry data may underestimate the rate of GnRH agonist use in men with prostate cancer.
    BMC Health Services Research 08/2008; 8:146. · 1.66 Impact Factor