TechTool Thursday 055 Sensitivity and Specificity

TechTool review Sensitivity and Specificity by Jolis Biotech on Android and iOS

Sensitivity and Specificity is an app by Dr Jolis and his colleagues, which does exactly what it says on the tin. It provides you with stats information for using blood tests, imaging, and other signs & symptoms to diagnosis disease. If you’re wondering why that would be useful, you need to check this app out. The database is huge.

Website: – Android –  iTunes – Website


It has a nice icon and splashscreen, but otherwise there’s nothing too wild to report about the design. It’s clear, readable and there were no problems with navigating my way around the app.

User Interface



Clinical Content

This app contains so many different tests, you will never get tired of browsing through it.To give an example, if you think your patient has appendicitis and are reviewing the CT scan, you can see stats on appendicitis by…

  • Ultrasound (male and female)
  • CT
  • Abscess on CT
  • Adenopathy on CT
  • Appendolith on CT
  • Arrowhead sign on CT
  • Ileal wall thickening on CT
  • Psoas sign
  • Actually there are about another 10 tests related to appendicitis but you get the general idea…

Each topic gives you the sensitivity and specificity of that test. There is also a box for negative predictive value (but I couldn’t find any tests with that value entered). There is a journal reference for each test to indicate where the stats data came from.

Finally, there is the option on the Sensitivity and Specificity website to add a new entry to their database. I always love resources that use crowdsourcing from the medical community.


  • FREE

Room for Improvement

  • A link to the reference would be helpful
  • A general description of sensitivity and specificity in the app information would be handy as many people get confused between the two


  • This is a great website with user-friendly Android and iOS versions.
  • Before doing any investigations or when delivering the results, a quick check of the sensitivity and specificity of the test can help form your decision and counseling.
  • This app is free, crowd-sourced, and a great initiative. We should all have this on our mobiles.

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  1. Cynthia Bierl says

    Hmmm… Interesting. But could falsely instill test confidence or falsely take it away. In clinical practice the npv/ppv are what’s important and depend on population prevalence (the reported npv column seems mostly empty but depends on the study patient population prevalence). In the absence of known prevalence the LR’s are more important in clinical practice and I think would be more useful to report (though easily calculable)??

    • says

      I agree Cynthia -- sensitivity and specificity are of little use to the diagnostician -- need to use likelihood ratios in conjunction with pre-test probabilities.

  2. Pik Mukherji says

    Thanks Dr. Davis,

    Cynthia +1000! I think this is a great step in the right direction but would be clinically much more useful with LR/PV values. High sens/spec can instill false confidence. Now that we offer screening for HIV in our US EDs, I commonly have people guess what the PPV is on a positive screen with s/s of 99.3/98.5.

    It’s close to 50%.

    Next biggest useful thing would be a range for cost of test!