The Clinical Software Usability Scale


Following the pattern established by the scoring of the established, pan-industry, Systems Usability Scale (SUS) 8, the questions are scored against a 5-point scale Agree Strongly — Agree — Don’t Know — Disagree — Disagree Strongly

The Clinical Software Usability Survey questions are:

  1. In my opinion, the software reduces the risk of clinical error. (positive)
  2. Effective support for this software is hard to access in a clinically-appropriate timescale. (negative)
  3. In my opinion, the software improves the quality of clinical care I can provide. (positive)
  4. The quality of the interaction/consultation with the patient is adversely affected by the use of this software. (negative)
  5. Using the software gives me the key information I need on patient’s history, diagnosed conditions and current care and treatment plan. (positive)


  • Each question scores from 0 to 4 points, where 0 signifies a trait of the least usable system and 4 signifies a trait of the most usable system. Clearly, because the ‘axis’ of the questions is alternated, the mathematics of the scoring must be alternated too. It makes the scoring a little bit complicated, again this is how it’s done is the SUS so we followed suit.
  • The points are summed to give a total for the cSUS score in which the minimum score is 0 and the maximum score is 20. They are then multiplied by a factor of 2.5 to give a score ranging from 0 to 50. The authors of SUS felt it necessary to include this multiplication step, which I believe is an unnecessary complication (and in fact, for those authors, resulted in completely avoidable confusion as to whether the SUS is a percentage 8), but we followed them in doing so in order to maintain compatibility/parity of weighting between SUS and cSUS.
  • In total therefore we end up with a SUS score out of 100 and a cSUS score out of 50. The total score for the combined survey is 150.



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Marcus Baw

Marcus Baw

#HIT100 NHS GP | Clinical Informatician | Ruby & Python dev | co-founder NHSbuntu & openGPSoC | Freelance Health IT