Week 1: Sore Throat Flashcards

Question

Accuracy for History and Physical Examination Elements in the Diagnosis of Strep Throat CHARTS (2)

Answer 1

A clinical decision rule (CDR) is a clinical tool that quantifies the individual contributions that various components of the history, physical examination, and basic laboratory results make toward the diagnosis, prognosis, or likely response to treatment in a patient. Attempt to formally test, simplify, and increase the accuracy of clinicians’ diagnostic and prognostic assessments. Existing CDRs guide clinicians, establish pretest probability, provide screening tests for common problems, and estimate risk.

Answer 2

Also know as the McIssac Score, the McIsaac Modification of the Centor Score, or the Adapted Centor Score A validated score to help predict the probability of streptococcal pharyngitis and guide clinical decision making Original Centor Score looked at 4 features: absence of cough (presence of cough suggest more viral illness), presence of fever, tonsillar exudates, and anterior cervical lymphadenopathy McIssac modified the score to include age as a feature Streptococcal pharyngitis is most common in ages 5-15 years It is rare in infants (< 3 years) and in adults > 45 years

Answer 3

Must be older than 3 years oldCough — No cough (+1)Exudates or swelling — Tonsillar exudates/swelling (+1)Nodes — Anterior cervical adenopathy (+1)Temperature — Hx of fever or temperature >38 (+1)Only Young — Patients <15yo (+1)Rarely Elder — Patients >45yo (-1)

Answer 4

aka rapid antigen detection test (RADT) Rapid screen for streptococcal antigens  if positive the patient is treated without follow-up cultures; if negative a throat culture is obtained Point-of-care test that can be done in office: rapid turnover time (minutes to 1 hour) compared to throat culture (about 48 hours) Swab collected from tonsils and posterior pharyngeal wall of patient Specificity 97%, Sensitivity 85%; LR+ 17.2, LR- 0.15 This video highlights how the test is performed: https://www.youtube.com/watch?v=-nOPDcAUOOc Newer nucleic acid tests offer better sensitivity Specificity 99%, Sensitivity 92% LR+ 92, LR- 0.08 Disadvantages: Rapid point-of-care testing cannot distinguish between carriers of GABHS and active infection, nor does it indicate antibiotic susceptibility or strain virulence

Answer 5

Gold standard for diagnosis of streptococcal pharyngitis (10% or lower false negative rate) Swab collected from tonsils and posterior pharyngeal wall of patient Sample from swab placed on a culture in the lab to observe for bacterial growth Culture showing growth of streptococcal species confirms the diagnosis

Answer 6

Benefits of antibiotic treatment of GABHS pharyngitis: Prevents acute rheumatic fever (NNT=4000) Decreases the transmission of GABHS Shortens the illness by 1 to 2 days (NNT=8) Reduces symptoms such as headache, sore throat and fever (NNT=6 to reduce symptoms after 3 days of treatment, NNT=21 after 1 week of treatment) May reduce suppurative complications Subsequent acute otitis media (NNT=29 in children, NNT=145 in adults) Subsequent acute sinusitis (NNT=50) Subsequent peritonsillar abscess (NNT=27) Most cases are self-limiting in 7-10 days even without antibiotics Harms of antibiotic treatment of GABHS pharyngitis: Shortens the illness by 1 to 2 days but no difference in time off school or work Has not shown to decrease risk of poststreptococcal glomerulonephritis or subsequent meningitis Harms of antibiotic treatment in general: Mild reactions: diarrhea, vomiting, abdominal pain, rash (NNH=10) Severe reactions: Clostridium difficile-associated diarrhea Life-threatening reactions: anaphylactic shock, sudden cardiac death

Answer 7

Many international guidelines consider GABHS pharyngitis self-limiting and do not recommend antibiotic treatment Delayed prescriptions decrease antibiotic use with no significant effect on symptom duration or clinical outcomes Populations with a higher incidence of GABHS complications, such as Indigenous people in Canada, might be more likely to benefit from antibiotic treatment Children are at a greater risk of complications (e.g., otitis media, peritonsillar abscess, rheumatic fever), may initiate antibiotic therapy sooner Carriers of GABHS do not require treatment At least 30% of GABHS cultured in primary care are due to carriers who are not sick and are at very low risk of infecting other people

Answer 8

Most cases are self-limiting in 7-10 days even without antibiotics, but Canadian guidelines suggest a full 10-day course of antibiotic therapy for confirmed GABHS infection For those with high likelihood of strep throat (i.e., score of 4 or more) with no signs of complications, a reasonable approach is watchful waiting and delayed prescription for antibiotics while waiting for culture results Advise patient to monitor symptoms and only fill the antibiotics prescription after confirmation of positive throat culture Another approach: empirical antibiotic therapy while waiting for throat culture results (and stop antibiotics if the culture is negative) Antibiotic therapy of choice: penicillin (unless patient has allergy) 5-day course of antibiotic therapy as clinically effective as 10-day course, although it might be less effective in eradicating GABHS infection Antibiotic therapy started within 9 days of symptom onset in confirmed GABHS will prevent rheumatic fever If the likelihood of streptococcal infection is low (i.e., Modified Centor score of 1 or less) or culture is negative, viral pharyngitis is likely. Provide supportive therapies and symptomatic relief: Analgesics (NSAIDs, acetaminophen, topical anesthetics) Throat lozenges or sprays Warm soothing drinks/liquids Gargle/rinse

Answer 9

aka mono or “kissing disease” Infection usually caused by Epstein-Barr virus (EBV) – more than 90% of cases Most common in ages 5-25 years Typical Presentation Gradual onset, low-grade fever, sore throat Malaise, fatigue Tonsillar exudates Palatine petechiae Lymphadenopathy (especially posterior cervical lymph nodes) Splenomegaly (50% of cases)  splenic rupture is an uncommon complication (0.1-0.5%) – highest risk in first 3 weeks of illness

Answer 10

Rapid screening test that detects heterophil antibody agglutination Best initial test for diagnosis of EBV infection – fast, inexpensive, has high specificity Can be conducted in-office Sensitivity 82%, specificity 99% LR+ 82, LR- 0.18

Week 1: Sore Throat Flashcards

(40 cards)