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Cancer Epidemiology
Published in Trevor F. Cox, Medical Statistics for Cancer Studies, 2022
Cohort studies are forward looking, where individuals are selected to be members of one or more cohorts, the selection being based on risk exposure and demographic variables. The cohort(s) are followed up for a certain period of time, with data collected on cancer outcomes and other variables. Data is often collected at various timepoints during the course of the study. This is a prospective cohort study which may take years to complete. Another type of cohort study is an historical cohort study or sometimes called a retrospective cohort study, where the data are obtained from historical records, appropriate individuals being selected for the cohort(s), again based on risk and demographic variables. Their records are then traced forward to see how the cancer outcome variables performed up to a particular time point. It is as if the researcher travels back in time and then conducts a prospective cohort study, eventually arriving back to the present.
The Form of Structural Equation Models
Published in Douglas D. Gunzler, Adam T. Perzynski, Adam C. Carle, Structural Equation Modeling for Health and Medicine, 2021
Douglas D. Gunzler, Adam T. Perzynski, Adam C. Carle
We used a retrospective cohort study design with data collected between 2008 and 2011. Inclusion criteria included individuals making at least one visit to the Mellen Center with measurements of PHQ-9 score and a timed 25-foot walk available. In the sample, typical of the United States’ MS population, the majority were female (73%) and Caucasian (83%). MS is typically diagnosed in individuals in their early 30s. In our sample, the average age was 46 (SD = 12). Also, in our sample, the average time since symptom onset was 10 (SD = 9) years ago with 81% relapsing and 16% progressive with the remaining patients falling into other categories, or under evaluation for a potential MS diagnosis. See Gunzler et al. [22] and Gunzler and Morris [23] for further description of the cross-sectional data and scales for this sample of persons living with MS which is used throughout this textbook.
Critical appraisal of retrospective studies
Published in O. Ajetunmobi, Making Sense of Critical Appraisal, 2021
Therefore, the methodology of a retrospective cohort study is somewhat similar to that of a prospective cohort study in that the exposure to risk factor is determined initially and only then are cohorts followed up regarding any subsequent events, including the development of outcome. As with any retrospective study, however, the main drawback of retrospective cohort studies is the potential for subject recall bias when ascertaining past exposures to risk factor.
Use of indwelling pleural catheters for patients with hematological malignancies and malignant pleural effusions
Published in Canadian Journal of Respiratory, Critical Care, and Sleep Medicine, 2022
Ali Malik, Michael A. Mitchell, Inderdeep Dhaliwal, Kayvan Amjadi
This study has limitations that should be addressed. Our study reports hematological malignancies broadly as lymphoma, leukemia, or multiple myeloma. However, there are various subtypes of each that may have different treatment options and prognosis. We did not analyze each subtype separately given the low numbers in some subgroups would have precluded any meaningful interpretation. Next, use of chemotherapy and other treatments options was not accounted for in the analysis given the heterogeneity and complexity of treatment durations and regimes for these patients. As discussed, the effectiveness of chemotherapy in reducing time to pleural effusion resolution remains an important topic for future research. Lastly, an important limitation of using a retrospective cohort study design is the potential for complications being missed if they were not identified in the health records. Patients may have sought care at alternative health care facilities which would not have been captured in our electronic medical records and, therefore, would lead to an underestimated incidence of complications.
The cost-effectiveness of biologic versus non-biologic treatments and the health-related quality of life among a sample of patients with inflammatory bowel disease in a tertiary care center in Saudi Arabia
Published in Journal of Medical Economics, 2020
Yazed AlRuthia, Majid Almadi, Abdulrahman Aljebreen, Nahla Azzam, Wejdan Alsharif, Hala Alrasheed, Ghadah Almuaythir, Maria Saeed, Baraa HajkhderMullaissa, Othman Alharbi
This investigation was designed as a retrospective cohort study. Patients 18 years of age or older, with a diagnosis of UC or CD and without a diagnosis of cancer, were identified using the electronic health records of King Khalid University hospital in Riyadh, Saudi Arabia. King Khalid University Hospital is a 1200-bed teaching hospital affiliated with King Saud University, which has the oldest school of medicine in the kingdom. The hospital provides tertiary care services to all Saudi citizens and legal residents on a referral basis, and has the largest IBD registry in Saudi Arabia. Two groups of patients who received treatment from January 2013 to December 2015 were compared; the groups consisted of patients treated with biologics alongside non-biologic therapies, and patients treated with non-biologic therapies only. The hospital’s IBD registry was used to retrieve data on the patients’ socio-demographic characteristics, resource utilization, disease behavior, and severity of the disease. HRQoL was assessed at the initiation of treatment and six months later using the Arabic version of the standardized EuroQol 5 Dimensional 3 Level (EQ-5D-3L) questionnaire with a visual analog scale (VAS)23,24. This was performed among a sample of newly referred patients to assess the impact of the treatments on patients’ HRQoL, and inform decisions related to the effectiveness of the prescribed treatment regimens. The study was approved by the Institutional Review Board of King Saud University College of Medicine (project no. E-11-538).
Prognostic factors affecting survival after whole brain radiotherapy in patients with brain metastasized lung cancer
Published in Acta Oncologica, 2018
Georgios Tsakonas, Fatou Hellman, Michael Gubanski, Signe Friesland, Salomon Tendler, Rolf Lewensohn, Simon Ekman, Luigi de Petris
We designed a retrospective cohort study. The patient population consisted of subjects with brain metastasized lung cancer who received palliative WBRT (no patient received adjuvant or prophylactic WBRT) at Karolinska University Hospital from the first of January 2010 until the first of January 2015. We collected demographic data, information about received oncological therapy, radiological evaluation, histopathological results and physician evaluation of performance status before receiving WBRT. Sixteen patients received a radiation dose of 3 Gy ×10 while the rest received 4 Gy ×5. Ethical approval was obtained from the regional ethical review board of Stockholm.