Critical value reporting: a survey of 36 clinical laboratories in South Africa

Critical value policies are used by clinical laboratories to decide when to notify caregivers of life-threatening results. Despite their widespread use, critical value policies have not been published locally. A survey was designed to determine critical value policies for haematology tests in South Africa.

A survey was carried out on 136 identified laboratories across South Africa in January 2013. Of these, 36 responded. Data collected included critical value policies, critical values for haematology parameters, and critical value reporting.

Of the 36 laboratories surveyed, 11.1% (n=4) were private, 33.3% (n=12) were affiliated to academic institutions and 55.6% (n=20) were peripheral or regional National Health Laboratory Service laboratories. All the laboratories confirmed that they had a critical value policy, and 83.3% of such policies were derived from local clinical opinion. Mean low and high critical limits for the most frequently listed tests were as follows: haemoglobin <6 and >20 g/dl, platelet count <41 and >1 000 ×10(9)/l, white cell count <2 and >46 ×10(9)/l, activated partial thromboplastin time >101 seconds, and international normalised ratio >6. In almost all cases critical value reporting was performed by the technologist on duty (97.2%). The majority of laboratories required that the person notified of the critical value be the doctor who ordered the test or the caregiver directly involved in the patient's care (83.3%); 73.3% of laboratories indicated that they followed an algorithm if the doctor/caregiver could not be reached.

Each laboratory is responsible for establishing clinically relevant critical limits. Clinicians should be involved in developing the laboratory's critical value policy. The findings of this survey may be of value to local laboratories that are in the process of establishing or reviewing critical value policies.