Sensitivity, Specificity, PPV, NPV

Sensitivity is TRUE POSITIVE RATE.

2x2 table 

Sensitive test picks all diseased and also sometimes without disease. That means it won’t miss the disease.

Sensitivity is a measure of  test positive out of total diseased. 

Specificity is TRUE NEGATIVE RATE.

Specific test picks only the diseased one but may sometime miss the disease itself.

Sensitivity and specificity are not dependent upon the disease prevalence rate.

Specificity is measure of true negative out of total healthy patient. 

Predictive values depend upon the prevalence of disease and accuracy of the test.

Positive Predictive Value is the proportion of the people with positive test who actually have disease.

Negative Predictive Value is the proportion of the people with negative test who actually do not have disease.

	PPV	NPV
Definition	% that a person with positive test is actually diseased.	% change that a person with negative test is actually disease free.
Use	Proceed with a patient with positive test	Proceed with a patient with negative test
Relation to prevalence	Low prevalence low PPV High prevalence high PPV	High prevalence low NPV Low prevalence High NPV

Paradise Criteria for Tonsillectomy

The Paradise criteria for tonsillectomy was given by AAO-HNS for tonsillectomy in paediatric and adolscent age group.

Minimum number of sore throat in a year

            Atleast 7 in the previous year

            OR Atleast 5 in each of two previous years

            OR Atleast 3 in each of three previous years

With Clinical feature of Sore throat along with atleast one of the following

            Fever > 100.9^oF (38.3^oC )

            OR Tender Cervical Lympadenopathy of size > 2 cm

            OR Tonsillar exudate

            OR Culture positive for GABH (Group A β Hemolytic Streptococcus)

With Administration of adequate dosing of ANTIBIOTIC for proven or suspected GABH infection. 

Know the difference between membranous tonsillitis and diptheria.

What are the causes of membranes over the tonsils?

Difference between adenoid and Tonsils.

Do you know how your examiner wants to hear the examination of oral cavity during your OSCE and Clinical Skills. Follow link.

Modification in Acute Rheumatic Fever Diagnostic Jones Criteria

The previously recommended diagnostic criteria used in Acute Rheumatic Fever has been modified in 2014 by the WHO and American Heart Association. Segregartion of the risk group into High risk and low risk group is an important feature.Low risk population are those who have incidence of RHD (Rhematic Heart disease) less than or equal to 1/1000 population/year and incidence of ARF (Acute Rheumatic Fever ) less than or equal to two /100000 population.

The previously accepted Jones Criteria still holds true for the low risk population.

HOWEVER, in the high risk population just the presence of MONOARTHRITIS or POLYARTHALGIA is sufficient to diagnose the ARF as MAJOR CRITERIA unlike in previous system where polyarthritis was must. 

Similarly in Minor Criteria the presence of MONOARTHALGIA is sufficient to daignose the condition. The value of ESR measured on the 1st hour with a value >= 30mm/hr is sufficeint  in low reisk populationwhile that of >= 60mm/hr is needed in low risk population to consider acute  rheumatic fever.

Presence of Clinically evident Sydenham Chorea is enough to diagnose the ARF.

Similarly, Arthritis with Carditis is enough to diagnose the condition.

Presence of Subcutaneous nodule or Erythema Marginatum with one of the major criteria diagnoses the condition.

Revised Jones Criteria 2014
Screenshot taken from http://circ.ahajournals.org/content/early/2015/04/23/CIR.0000000000000205

Visit http://circ.ahajournals.org/content/early/2015/04/23/CIR.0000000000000205 the site and download the PDF file for full details.