Sensitivity, Specificity, and Acceptability of a Bedside Formate Assay as a Diagnostic Tool in Methanol Poisoning: Prospective Observational and Randomized Studies
Methanol poisoning is a serious issue, particularly in low- and middle-income countries (LMICs), where outbreaks can devastate communities. Diagnosing methanol poisoning is challenging because its symptoms mimic many other conditions, and traditional diagnostic methods require expensive lab equipment. Unfortunately, this often means doctors do not even consider methanol poisoning as a diagnosis. Methanol itself isn't highly toxic, but when the body breaks it down into formate, it becomes dangerous, leading to brain swelling and even death. To address this, a study team has developed a new method to diagnose methanol poisoning using a single drop of blood with a device that can be used at the bedside, eliminating the need for any lab equipment. This point-of-care (POC) test measures formate, which is only present in cases of methanol poisoning. The project consists of two sequential studies. The first study aims to compare the effectiveness of the POC formate test against standard lab tests, which can take several hours. The findings from this study will inform the second study. The second study is a feasibility cluster randomized controlled trial. In this trial, entire hospitals, rather than individual patients, are randomly assigned different approaches, similar to tossing a coin. The goal is to determine whether this trial design can be used in larger-scale research to evaluate clinical outcomes. Specifically, it will examine whether the POC formate test can accelerate accurate diagnosis, enabling prompt treatment and preventing deaths.
• • Patients presenting with suspected methanol poisoning or metabolic acidosis of unknown cause, including:
• Children aged 16-17 years, who are willing to provide assent.
• Parents/Guardians of children who are able and willing to provide consent.
• Adults (aged 18 years with no upper age limit) who are willing to provide informed consent.
• Participants who lack capacity to consent for themselves but who have a relative who is willing and able to provide informed consent on behalf of the participant.
• Suspected methanol poisoning will be based on clinician judgement using the following typical indicators of possible methanol ingestion:
⁃ History of:
∙ Intake of illegal/bootleg/spurious alcohol, and/or
‣ Other patients admitted with confirmed/suspected methanol poisoning and/or
‣ Time from intake to symptoms \>6-12 h
⁃ Symptoms/clinical findings
∙ Coma, and/or
‣ Hyperventilation (respiratory rate \[RR\] \>20/min) and/or dyspnea, and/or
‣ Visual disturbances (blurred vision, blindness), and/or
‣ Gastrointestinal symptoms (vomiting, abdominal pain), and/or
‣ Chest pain, and/or
‣ Severe/unusual 'hang-over': Feeling very sick the following day, and/or
‣ Pseudopapillitis
• Metabolic acidosis of unknown origin will be based on the following features:
• Metabolic acidosis of unknown origin = origin not identified. The acidosis is not of unknown origin if the metabolic acidosis can be explained by another cause eg. lactic acidosis (e.g. where base deficit \[BD\] = 15 mM \[i.e., base excess (BE) = -15 mM\] and lactate is 12-15mM).
• An initial ABG shall be drawn. If the BD is \>15mM (BE\<-15mM), the patient shall be included (as long as unknown origin - see above). If the patient has a BD between 5-15, the acidosis is only moderate, and there is time to do the fluid trial (see below). If the acidosis improves within 1-2 hours after the fluid trial, the acidosis is unlikely to be because of methanol and the patient should not be included. If the acidosis does not improve, the patient should be included.