Charlson ME, Pompei P, Ales KL, MacKenzie CR A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis. 1987;40(5):373-83. doi: 10.1016/0021-9681(87)90171-8.
Friedman RJ, Hess S, Berkowitz SD, Homering M Complication rates after hip or knee arthroplasty in morbidly obese patients. Clin Orthop Relat Res. 2013 Oct;471(10):3358-66. doi: 10.1007/s11999-013-3049-9. Epub 2013 May 14.
Kerkhoffs GM, Servien E, Dunn W, Dahm D, Bramer JA, Haverkamp D The influence of obesity on the complication rate and outcome of total knee arthroplasty: a meta-analysis and systematic literature review. J Bone Joint Surg Am. 2012 Oct 17;94(20):1839-44. doi: 10.2106/JBJS.K.00820.
Lozano LM, Nunez M, Segur JM, Macule F, Sastre S, Nunez E, Suso S Relationship between knee anthropometry and surgical time in total knee arthroplasty in severely and morbidly obese patients: a new prognostic index of surgical difficulty. Obes Surg. 2008 Sep;18(9):1149-53. doi: 10.1007/s11695-008-9481-3. Epub 2008 May 28.
Malinzak RA, Ritter MA, Berend ME, Meding JB, Olberding EM, Davis KE Morbidly obese, diabetic, younger, and unilateral joint arthroplasty patients have elevated total joint arthroplasty infection rates. J Arthroplasty. 2009 Sep;24(6 Suppl):84-8. doi: 10.1016/j.arth.2009.05.016. Epub 2009 Jul 15.
Messier SP, Callahan LF, Golightly YM, Keefe FJ OARSI Clinical Trials Recommendations: Design and conduct of clinical trials of lifestyle diet and exercise interventions for osteoarthritis. Osteoarthritis Cartilage. 2015 May;23(5):787-97. doi: 10.1016/j.joca.2015.03.008.
Namba RS, Paxton L, Fithian DC, Stone ML Obesity and perioperative morbidity in total hip and total knee arthroplasty patients. J Arthroplasty. 2005 Oct;20(7 Suppl 3):46-50. doi: 10.1016/j.arth.2005.04.023.
Parvizi J, Trousdale RT, Sarr MG Total joint arthroplasty in patients surgically treated for morbid obesity. J Arthroplasty. 2000 Dec;15(8):1003-8. doi: 10.1054/arth.2000.9054.
Rikli RE, Jones CJ Development and validation of criterion-referenced clinically relevant fitness standards for maintaining physical independence in later years. Gerontologist. 2013 Apr;53(2):255-67. doi: 10.1093/geront/gns071. Epub 2012 May 20.
Roos EM, Lohmander LS The Knee injury and Osteoarthritis Outcome Score (KOOS): from joint injury to osteoarthritis. Health Qual Life Outcomes. 2003 Nov 3;1:64. doi: 10.1186/1477-7525-1-64.
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.
