Farbood A, Sahmeddini MA, Bayat S, Karami N The effect of preoperative depression and anxiety on heart rate variability in women with breast cancer. Breast Cancer. 2020 Sep;27(5):912-918. doi: 10.1007/s12282-020-01087-y. Epub 2020 Apr 7.
Hogan AM, Luck C, Woods S, Ortu A, Petkov S The Effect of Orthostatic Hypotension Detected Pre-Operatively on Post-Operative Outcome. J Am Geriatr Soc. 2021 Mar;69(3):767-772. doi: 10.1111/jgs.16966. Epub 2020 Dec 11.
Ideguchi M, Kajiwara K, Yoshikawa K, Sadahiro H, Nomura S, Fujii M, Suzuki M Characteristics of intraoperative abnormal hemodynamics during resection of an intra-fourth ventricular tumor located on the dorsal medulla oblongata. Neurol Med Chir (Tokyo). 2013;53(10):655-62. doi: 10.2176/nmc.oa2012-0401. Epub 2013 Sep 27.
Padley JR, Ben-Menachem E Low pre-operative heart rate variability and complexity are associated with hypotension after anesthesia induction in major abdominal surgery. J Clin Monit Comput. 2018 Apr;32(2):245-252. doi: 10.1007/s10877-017-0012-4. Epub 2017 Mar 14.
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.