## 1 Introduction
\begin{table}
\begin{tabular}{p{34.1 pt} p{284.5 pt}} \hline \hline
**Question** & A 27-year-old male presents to urgent care complaining of pain with urination. He reports that the pain started 3 days ago. He has never experienced these symptoms before. He _denies gross hematuria or pelvic pain_. He is sexually active with his girlfriend, and they consistently use condoms. When asked about recent travel, he admits to recently returning from a “boys” trip” in Cancun where he had _unprotected sex_ 1 night with a girl he met at a bar. The patient’s medical history includes type I diabetes that is controlled with an insulin pump. His mother has rheumatoid arthritis. The patient’s temperature is 99 \({}^{\circ}\)F (37.2 \({}^{\circ}\)C), blood pressure is 112/74 mmHg, and pulse is 81/min. On physical examination, there are no lesions of the penis or other body rashes. No costovettebral tenderness is appreciated. A urinalysis reveals no blood, glucose, ketones, or proteins but is _positive for leukocyte esterase_. A urine microscopic evaluation shows a _moderate number of white blood cells_ but no casts or crystals. A urine culture is negative. Which of the following is the most likely cause for the patient’s symptoms? \\ \hline
**Options** & **A: Chlamydia trachomatis, B: Systemic lupus erythematosusous, C: Mycobacterium tuberculosis, D: Treponema pallidum** \\ \hline
**Evidence** & At least one-third of male patients with C. _tachomatis_ urethral infection have _no evident signs or symptoms of urethritis_.... Such patients generally have _pyuria..._, a _positive leukocyte esterase test_,... \\ \hline
**Question** & A 57-year-old man presents to his primary care physician with a 2-month history of _right upper and lower extremity weakness_. He noticed the weakness when he started falling far more frequently while running errands. Since then, he has had _increasing difficulty_ with walking and lifting objects. His past medical history is significant only for well-controlled hypertension, but he says that some members of their _family have had musculoskeletal problems_. His right upper extremity shows _ forearm atrophy_ and _depressed reflexes_ while their right lower extremity is _hypertonic with a positive Babinski sign_. Which of the following is most likely associated with the cause of this patient’s symptoms? \\ \hline
**Options** & A: HLA-B8 haplotype, B: HLA-DR2 haplotype, **C: Mutation in SOD1, D: Mutation in SMN1, E: Viral infection \\ \hline
**Evidence** & 1. The manifestations of ALS... _isdiously_ developing _asymmetric weakness_, usually first evident distally in one of the limbs. 2.... _hyperactivity of the muscle-stretch reflexes (tendon jerks_) and, often, _spastic resistance to passive movements_... 3. _Familiar ALS (FALS)..._ clinically indistinguishable from sporadic ALS.. Genetic studies have identified mutations in multiple genes, including cytosolic enzyme _SOD1..._ \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Two examples of MedQA (Medical Question Answering). The correct answer among options is marked in bold font. Key words in the question and evidence text to help answer the questions are highlighted in italic font. Evidence for both examples are from the textbook “Harrison’s Principles of Internal Medicine”. this dataset. Through both quantitative and qualitative analysis, we find that the performance of document retriever should be the bottleneck since its current form cannot conduct multi-hop reasoning over the retrieving process. Our hope is that MedQA can serve as a platform to encourage researchers to develop a general OpenQA model that can solve complex real-world questions via abundant logical reasoning in both retrieval and comprehension stages.