USMLE Step 1 vs. COMLEX Level 1: Differences in Format and Categories
As you probably already know, the COMLEX Level 1 and USMLE Step 1 exams serve the same core purpose: to assess the fundamental medical knowledge necessary to advance to the third year of medical school for MD (USMLE) and DO (COMLEX) students. However, they differ quite dramatically in how they are written, what they emphasize, and how best to prepare for each one.
Differences Between COMLEX and USMLE Exams
The exams themselves are fundamentally different.
| Exam Feature | COMLEX Level 1 | USMLE Step 1 |
|---|---|---|
| Minimum Passing Score | 400 | 194 |
| Number of Test Items | 400 MCQs | 280 MCQs |
| Length of Exam | Two four-hour sections consisting of four 50-question blocks each; 8 hours of total exam time | Seven 60-minute blocks; 8 hours of total exam time |
| Number and Length of Breaks | Two 10-minute breaks and one 40-minute lunch break | 45-minute break, self-scheduled and must be taken between blocks. If you complete the tutorial or other testing blocks early, the remaining time will be added to your total break time. |
| Topic Emphasis | Greater emphasis on microbiology, pharmacology, MSK, and neurology compared to USMLE Step 1. | Greater emphasis on biochem compared to COMLEX Level 1. Step 1 also places a big emphasis on Pathology (~50% of exam). |
| Osteopathic Manipulative Medicine (OMM) | Yes | No |
| Management Emphasis | Approximately 5% of exam may be questions concerning management. | Currently 7-12% of questions categorized as Patient Care: Management; however, the content distribution is set to change in October 2020 |
| Videos | Longer in length, some exceeding 60 seconds, almost entirely MSK and OMM | Some items have associated images, audio clips, or video clips. Some of these media may be interactive. |
| Stems | COMLEX stems may have information in them that is extraneous (not necessary to answer the question) | Step 1 stems avoid “window dressing” (extraneous material not needed to answer the item) and “red herrings” (information designed to mislead the test-taker) |
| Sentence Construction | COMLEX constructions are more varied. | USMLE has a conserved syntax and grammatical consistency that is not seen in COMLEX |
| Exam Interface | Preview the interface and prepare for exam day with this Tutorial. | Preview the interface and prepare for exam day with this Tutorial. |
| Content Outline | Follows the NBOME Blueprint | Follows the USMLE Content Outline |
Differences in Subject Matter
In general, both exams test the fundamental knowledge of medicine that a third-year medical student should know, with a roughly equal distribution of questions on each body system. Level 1 does significantly emphasize the musculoskeletal/integumentary system more than Step 1, with 18% vs 6-10% of questions within this category, respectively. On top of that, 11% of Level 1 questions cover osteopathic manipulative medicine (OMM), the musculoskeletal treatment techniques for various injuries and diseases specific to DO trainees, which is obviously not covered on Step 1.
Another significant difference is the emphasis on basic science/biochemistry. Step 1 focuses 14-24% of the questions on “biochemistry and nutrition,” whereas Level 1 does not have a defined category or percentage listed. This difference is easily noticed on exam day and manifests as detailed biochemistry, genetics, organic chemistry, pharmacology, and scientific research questions on Step 1 that are not seen nearly as frequently on Level 1. For example, Step 1 may ask you to identify the specific gene or function involved, whereas Level 1 will more commonly ask for the diagnosis or first step in work-up.
Another broader difference reflected in the blueprint/content outline for each exam is the Level 1 emphasis on clinical care, including diagnosis, management, OMT, patient interaction, etc., compared to Step 1’s greater emphasis on physiology, pathophysiology, pathology, and basic science. This is a key difference to realize and keep in mind while preparing for each exam, as it should change where the focus lies when studying a given topic. This is not to say either exam will not test any of these categories, but rather to acknowledge the noticeable difference of emphasis and quantity of questions within each category.
Best Way to Prepare for Each Exam
Here are 5 things I would recommend when studying for each exam:
| USMLE Step 1 | COMLEX Level 1 | |
| 1 | Thoroughly review basic biochemistry, genetics, physiology, and pathophysiology. | Dedicate time to review OMT diagnosis and techniques. |
| 2 | Spend more time focusing on pathology using a specific review source. | Spend more time reviewing microbiology with a dedicated resource. |
| 3 | Review the mechanisms and biochemistry of common medications and antibiotics. | Focus on making diagnoses and understand basic pathologic principles. |
| 4 | Familiarize yourself with images of normal anatomy and common pathology (x-rays, CT scans, histology, etc.) | Be prepared for videos demonstrating physical exam maneuvers or OMT. |
| 5 | Be able to apply physiologic principles to theoretical situations or experiments. | Become comfortable with musculoskeletal injuries, pathology, and basic management. |
Written By: Dustin Dehart, DO | PGY II General Surgery, Chicago, IL
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