Established in 2004, the Certificate for OASIS Specialist-Clinical (COS-C) exam is the premier, nationally standardized, psychometrically validated test that evaluates an individual's knowledge of CMS' OASIS guidelines. Domains covered by the COS-C exam include OASIS regulations, data collection time points, patient populations, data collection conventions and OASIS data set item-by-item guidance. Since its inception, more than 28,000 candidates have participated in the exam process.
About the COS-C Exam
The COS-C exam was originally developed and administered by the OASIS Certificate & Competency Board (OCCB). The COS-C exam is a voluntary certificate examination available to home care providers interested in demonstrating and establishing their expertise and commitment to OASIS data accuracy. Exam administrators go to great lengths to ensure that the COS-C exam is an accurate reflection of the most current CMS guidance, and that it is administered in a way to protect the integrity of the resulting COS-C designation. This requires vigilance in both exam analysis and proctoring efforts. Candidates agree to respect test integrity by participating in a confidentiality agreement.
Two Ways to Take the COS-C Exam
Exam format and content is the same for each of these options. You may choose to register for the option that is convenient for you and fits your needs.
• Paper & Pencil Test @ Workshop Location
• Computer Based Test @ Testing Center
The Psychometric Process
The exam items are developed by the COS-C Exam Review Committee, a group of OASIS content experts of varied home health backgrounds and disciplines, who create these items to reflect the OASIS knowledge and skills identified as necessary for competent OASIS data collection. The test undergoes a holistic review by a psychometrician and the Committee examining the test for accuracy, significance, fairness, and conformity to test specifications. A rigorous item analysis adhering to psychometric industry standards detects any questionable item performance. When item ambiguities are detected, the necessary adjustments are made before a passing score is determined. The COS-C exam is reviewed and regularly updated, including regular item analysis to determine that all test items are performing as originally intended.
This extensive psychometric process is necessary not only to verify each item as reliable and an appropriate representation of CMS' rules but also to determine that all questions are written in an accurate and fair manner. How a question is asked is as important as what the question is asking. Knowing that the COS-C exam meticulously covers CMS' OASIS guidance is not enough. Only when we statistically verify that each item is psychometrically and technically sound and ensure the test is administered in a conducive and protected environment, does the exam attain credibility; credibility that bestows value upon the resulting COS-C designation.
Exam Audience - Anyone interested can sit for the COS-C Exam. There are no requirements other than a desire to demonstrate your knowledge of CMS data collection guidance and commitment to OASIS data accuracy. Suggested professions: Home Health Nurses, Therapists or other home health professionals responsible for conducting comprehensive assessments, scoring OASIS items, auditing clinical records, educating or orienting staff
Exam Description - 2.5 hour exam duration, 100 multiple-choice questions. Exam results are reported as Pass or Fail. At Exam Check-in, candidates must present 2 forms of Identification, one of which must be valid government-issued ID.
Exam Content -The scope of the COS-C exam includes CMS rules and instructions related to the OASIS time points, regulations, patient populations & OASIS item specific scoring. The exam is open-book; candidates are allowed to bring ANY paper-based OASIS reference materials into the examination, including, but not limited to, CMS Core OASIS Documents, OASIS Guidance Manual, CMS OASIS Q&A’s, the Blueprint for OASIS Accuracy handout and an Instant OASIS Answers book.
For details on how to prepare for the exam and sample test questions go to, Exam Preparation
For exam instructions and protocols for each testing option refer to, Candidate Handbook
To check the current listing of those who have successfully passed the COS-C Exam, Check COS-C Status