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MODY Probability Calculator


This is for use in patients diagnosed with diabetes under the age of 35 and was developed on a European Caucasian cohort. (Shields et al. 2012, Diabetologia)

Enter the clinical features of the patient in the form below and press the "Calculate Probability" button.

Enter your details

Age at diagnosis (years)
Sex

Male Female

Currently treated with insulin or OHA? Yes No
Time to Insulin Treatment (if currently treated with insulin)

Not currently treated with insulin
Within 6 months of diagnosis
Over 6 months after diagnosis

BMI (kg/m2)
HbA1c (%)

or mmol/mol

Current Age (yrs)

Parent affected with diabetes?

Yes No


Results:

Based on the clinical features entered into the calculator, the post-test probability (Positive Predictive Value (PPV)) of your patient having MODY is % i.e. a 1 in chance or lower of testing positive for MODY. As , this is based on a background prevalence level for MODY of i.e. a 1 in chance of having MODY.



Further screening tests that can be done prior to genetic testing:

If your patient is insulin-treated you can improve the post-test probability by testing for endogenous insulin secretion using urinary C-peptide creatinine ratio (UCPCR) or for pancreatic autoimmunity using GAD/IA2 antibodies to rule out Type 1 diabetes. Both tests are highly specific and sensitive markers discriminating MODY from Type 1 diabetes (Besser et al. 2011; McDonald et al, 2011).


At what PPV level should I test?

The current pick-up rate for MODY testing in the UK is 25%, but where a diagnosis would make a difference to a patient's management, one might like to consider testing at a lower probability.

The higher the threshold, the less likely you are to pick up false positives (send patients for testing who are not MODY), but the more likely you are to miss a genuine case of MODY (false negatives).

  • If you use a PPV as the basis to refer for genetic testing you would expect to get false negatives and false positives for every 100 patients you test


  • If you use a PPV as the basis to refer for genetic testing you would expect to get false negatives and false positives for every 100 patients you test


  • If you use a PPV as the basis to refer for genetic testing you would expect to get false negatives and false positives for every 100 patients you test


If you would like to learn more about MODY, please click here


We have assumed background prevalences of 0.7% MODY for those who are insulin treated within 6 months of diagnosis, and 4.6% MODY for those who are not treated insulin treated within 6 months of diagnosis.


The Diabetes Diagnostics app is now available in the App Store for Apple devices, combining the MODY clinical prediction calculator, information from national and international diabetes guidelines, and expert opinion from world leaders in monogenic diabetes to provide a resource to help guide diabetes classification.

Diabetes Diagnostics Diabetes Diagnostics

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