What investigations are essential for confirming a diagnosis of rheumatic fever in primary care?

Essential investigations for confirming a diagnosis of rheumatic fever in primary care primarily involve clinical assessment supported by laboratory tests to detect evidence of recent group A streptococcal infection and inflammation.

These investigations include:

• Throat swab culture or rapid antigen detection test to identify group A streptococcal infection, if the patient presents with a sore throat or recent pharyngitis.
• Blood tests for inflammatory markers such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), which are typically elevated in rheumatic fever.
• Antistreptolysin O (ASO) titre or anti-DNase B antibodies to demonstrate a recent streptococcal infection, especially if throat swab is negative or not possible.
• Electrocardiogram (ECG) to detect any cardiac involvement such as prolonged PR interval.
• Chest X-ray may be considered if carditis is suspected to assess cardiac size and pulmonary status.

Definitive diagnosis often requires specialist assessment and echocardiography to evaluate for carditis, which is beyond primary care scope.

Note: The provided UK guidelines do not explicitly detail rheumatic fever investigations; however, standard clinical practice and NICE-related resources emphasize these investigations as essential initial steps in primary care to support diagnosis and referral.