A Cohort Study Critique - Essay Example

? A Cohort Study Critique The incidence of cancer is believed to be higher in HIV-infected persons in comparison with the general population; hence, a group of investigators conducted a study to determine whether such premise is true in lieu of a variety of factors. Keywords: incidence, cancer, HIV-infected persons, general population A Cohort Study Critique The study, entitled “Incidence of Types of Cancer among HIV-Infected Persons Compared with the General Population in the United States, 1992-2003”, conducted by Patel et al. (2008), aimed in identifying and comparing the incidence of cancer among persons with HIV and the general population during the period from 1992 to 2003. This paper endeavors to make a critique of the aforementioned cohort study article. Research Question The research question chosen by this study was very interesting and informative. Moreover, it could help the medical field to determine whether a particular type of group may be more at risk compared to the typical population for the study aimed to discover “whether HIV-infected persons may be at higher risk of having several types of cancer in comparison with the general population from 1992 to 2003” (Patel et al., 2008). Health Outcome of Interest The main interest in conducting the study was to determine the “incidence of cancer in persons with HIV in comparison with the general population from 1992 to 2003 and to know what types of cancers the said population group was more prone of having” (Patel et al., 2008). This study was fruitful to its readers for the reason that it provides awareness of two common medical conditions that individuals are experiencing. It also helps in sharing the contributing risk factors which will increase the likelihood of aggravating the aforementioned disease conditions; thus, providing the individuals the chance to prevent such factors in the future so as to decrease the probability of acquiring the said diseases. Exposure of Interest The study was conducted to learn reliable data which will present “the incidence of cancer in HIV-infected persons and the general population from 1992-2003 which focused primarily in the United States” (Patel et al., 2008). The said country was, probably, chosen by the authors due to the high incidence of the abovementioned diseases in that country despite being an advanced country possessing the means to develop technologies in preventing such diseases. Moreover, since this is the fact, determining the probable root causes of the problem may cause them make innovations that could not only benefit them but also neighboring countries that are relying on their expertise. Type of Study The type of study utilized by Patel et al. (2008) was a prospective observational cohort study which is a surveillance project established by the Centers for Disease Control and Prevention in collaboration with a variety of affiliated health care centers in 11 geographical areas, namely, Atlanta, Georgia; Los Angeles, California; Dallas, Houston and San Antonio, Texas; Denver, Colorado; Detroit, Michigan; New Orleans, Louisiana; New York City, New York; Seattle, Washington; and Bayamon, Puerto Rico. The study recruited and followed HIV-infected patients age 18 years or older since 1992 and the data collected by the participating centers and clinics such as sociodemographic characteristics, HIV risk factors, symptoms, both definitive and presumptive, medications prescribed, CD4 lymphocyte counts and all other laboratory test results (Patel et al., 2008). Cases of cancer are defined by using clinical information about new cancer diagnoses; moreover, it collects incidence and survival data among the said population (Patel et al., 2008). The study utilized by the authors was very practical and decreased the likelihood of intervening with the findings of the study for the investigators adapted to the natural means of obtaining the information that was necessary, and they did not exhibit any form of result manipulation. Description/Ascertainment of Cohort and Data Collection at Baseline The individuals chosen by the investigators targeted a group that would be representative of the population and they were able to give justice to their aim. The investigators of the study identified HIV-infected patients age 13 years or older and conducted an initial medical record review for the 12 months preceding enrollment to document socio-demographic characteristics, HIV risk factors, occurrence of AIDS-defining opportunistic illnesses according to the 1993 revised AIDS surveillance definition from the CDC, other illnesses, including cancer, medication use, CD4 lymphocyte counts and other relevant laboratory test results, as well as hospitalizations or other uses of the medical system (Patel et al., 2008). Thereafter, investigators conducted follow-up medical record reviews every 6 months to collect matching interval data (Patel et al., 2008). The data collection was simple but entailed a lot of hard work. The project in question collected detailed information about cancer diagnoses, including anatomical site, morphology, and International Classification of Diseases, Ninth Revision, codes; the investigators enrolled more than 60,000 HIV-infected persons and collected more than 180,000 person-years of observation (Patel et al., 2008). Type, Frequency and Duration of Follow-up As previously mentioned, the investigators of the study conducted follow-up medical record reviews every 6 months to collect matching interval data of the enrolled participants (Patel et al., 2008). This manner was effective and efficient for the reason that it really kept track of the condition of the participant noting any changes or progress with his/her condition. Type of Data Analysis The authors of the study were guided by an established form of analysis utilized by a lot of previous studies which could prove the accuracy, validity and reliability of the results derived from the study. The authors of the above-mentioned study utilized statistical analysis by calculating the incidence rates for persons 15 to 84 years of age as the collective number of newly diagnosed cancer cases annually for the overall analysis period (1992 to 2003) and the pre-HAART or highly active antiretroviral therapy from 1992 to 1995, early HAART from 1996 to 1999, and recent HAART (2000 to 2003) subperiods to account for the transition to and stabilization of HAART use (Patel et al., 2008). Incidence rates were expressed per 100,000 prospective person-years of observation during these same periods, as mentioned by Patel et al. (2008). Person-years varied slightly for each cancer type due to the exclusion of prevalent cases; person-years at risk for cancer were computed after HIV diagnosis from date of enrollment (Patel et al., 2008). Standardized rate ratios for the entire observation were utilized supposing that the standardization group followed a Poisson distribution; conversely, to evaluate trends over time in incidence of specific cancer types in the HIV-infected population, the investigators employed the use of multivariable Poisson regression in a model controlling for age, race, sex, HIV risk group, nadir CD4 count and antiretroviral therapy (Patel et al., 2008). Results/Main Findings of the Study The incidence of the following types of non–AIDS-defining cancer was significantly higher in the HIV-infected population than in the general population from 1992 to 2003, namely, anal, vaginal, Hodgkin lymphoma, liver, lung, melanoma, oropharyngeal, leukemia, colorectal and renal (Patel et al., 2008). The incidence of prostate cancer was significantly lower among increased over time, as discovered by Patel et al. (2008). The results derived from the study depicted the efforts made by the investigators in collecting and collating data so as to provide readers with accurate results that could be beneficial in determining and exploring the link between HIV and cancer. Assessment of Bias This study aimed as much as possible to limit biases; however, in some aspects, they failed to do so. The study of Patel et al. (2008) had limitations for the reason that lower ascertainment of cancer in the HIV cohorts results in a potential bias to underestimate rate disparities; whereas, tobacco use as a risk factor and the effect of changes in cancer screening practices could not be evaluated. Assessment of Confounders The extraneous variable, such as funding source, was proven to be invaluable to the findings of the study. As reiterated by the authors of the said study, the funding source had no role in the design, analysis, or interpretation of the data or in the approval of the manuscript (Patel et al., 2008). The incidence of cancer increased significantly in HIV-infected persons despite the advent of highly active antiretroviral therapy, meaning it may not be a crucial factor in determining cancer incidence (Patel et al., 2008). It was included, however, to prove a point that other factor may be more influential compared to others. Comments The study conducted by Patel et al. (2008) was very beneficial for it was able to determine if the incidence of cancer is higher in HIV-infected persons than in the general population. Moreover, they were able to investigate the varied factors that may contribute to the high incidence of the disease in the said risk group (Patel et al., 2008); hence, such information may be valuable in preventing the said illness in the future by effectively addressing the probable contributing risk elements that may expedite the development of cancer. However, for future studies, a more comprehensive research may be done so as to really determine the root cause why certain types of cancer are more apparent in HIV-infected persons compared to those who do not have the condition; it is also recommended that future studies scrutinize every little detail that can be extracted out of the information received from study participants. References Patel, P., Hanson, D.L., Sullivan, P.S., Novak, R.M, Moorman, A.C., Tong, T.C., Holmberg, S.D., & Brooks, J.T. (2008). Incidence of types of cancer among HIV-infected persons compared with the general population in the United States, 1992-2003. Annals of Internal Medicine, 148 (10), 728–736. Read More