Poisonings are a common type of injury in Aotearoa New Zealand.[[1,2]] They can be life-threatening, time-dependent emergencies requiring specialist input for optimal diagnosis and treatment. Since there are hundreds of thousands of chemical substances to a which a person may be exposed, there are myriads of unique poisonings with the potential to cause morbidity and mortality.

Medical (or clinical) toxicology is a field of medical practice that concerns itself with the evaluation, management and prevention of poisoning in all its forms. Historically, there have been few physicians in Aotearoa New Zealand who practised medical toxicology. Currently there are no formal training pathways available to obtain expertise in this field here, but physicians can develop knowledge through a small number of distance learning programmes, professional organisation conferences or by seeking formal training abroad. Overseas, there has been a small but increasing number of physicians seeking specific training in medical toxicology.[[3]] For example, in the United States, medical practitioners who have already attained a primary vocational scope will train for at least two additional years in medical toxicology, following an extensive curriculum that forms the basis for certification as a specialist medical toxicologist.[[4]]

Poisons centres are promoted by the World Health Organization (WHO) to operate as integral parts of the healthcare system, helping members of the public and healthcare professionals and providing multiple benefits.[[5]] For example, studies have demonstrated how poisons centres can save costs and resources by triaging patients when an exposure can be safely managed at home,[[6]] and by assisting primary care clinicians in managing patients and avoiding tertiary care presentations when appropriate.[[7]] In various settings and across multiple countries, consultations with poisons centres and involvement of medical toxicologists in patient care has been associated with a variety of benefits including decreased length of stay, reduced healthcare costs and reduced resource utilisation.[[8–13]]

The National Poisons Centre (NPC) operates with 15 full-time equivalent staff roles, two of which are medical toxicologist roles. The toxicologist roles are currently filled by registered, vocationally certified emergency medicine specialists who also have formal training and certifications in medical toxicology from overseas. The NPC also utilises a small casual pool of experienced emergency medicine specialists who have additional medical toxicology training to provide a few days of on-call availability throughout the year, with back-up available from the core medical toxicologists as required. Collectively, this group of specialists provide 24/7 availability for consultation and engage in peer review activities for governance of the clinical consultations provided. Healthcare professionals anywhere in Aotearoa New Zealand can contact the NPC any time to access real-time consultation and advice from medical toxicologists through its free phone number 0800 POISON (0800 764 766). Once connected with frontline NPC staff, healthcare professionals can request medical toxicologist consultation (or this may be offered by frontline staff if not requested by the caller) and then the caller is put in direct phone contact with the medical toxicologist, usually within a few minutes. Being a telehealth-based service, this aspect of NPC’s operation brings a limited and unique clinical expertise to all areas of the country with easy accessibility, which helps to promote health equity.

In late 2017, the NPC adopted new strategic goals to increase the links between the NPC and the clinical community with an aim to make medical toxicologist consultation more integrated across the broader healthcare system. A range of activities supported this goal, such as targeted outreach to clinician groups, educational sessions and discussion forums hosted by the NPC, revision of NPC protocols for consulting with medical toxicologists, word-of-mouth promotion and others. This study aimed to describe the contacts to the NPC where one of its medical toxicologists was consulted and provided management advice between 2018–2020. This information will highlight relevant areas where NPC medical toxicologists offer advice to clinicians in their patient care.

Methods

Ethical approval was obtained from the University of Otago Human Research Ethics Committee (ref: HD19/064), and the study was conducted according to the principles of the Declaration of Helsinki.[[14]] All data were de-identified before analysis.

This was a retrospective study utilising the NPC’s electronic medical record database to characterise contacts about human patients who had been exposed to various substances and where a medical toxicologist was consulted. All matching records from 1 January 2018 to 31 December 2020 were included in the study. It should be noted that a record may not always necessarily correspond to a single unique patient and exposure, as there may be multiple contacts to the NPC about the same incident and patient. Such records are considered “linked records”. As linked records may overestimate the incidence of unique exposures, this study does not attempt to determine population prevalence rates for poisoning, but simply a crude rate of numbers of contacts in proportion to the district health board (DHB) or national population size. The subnational population estimates (DHB, DHB constituency) on 30 June of each respective study year were used as the population number for calculating crude rates.[[15]] The rate of linked records was determined for reference. Records where the person contacting the NPC was a healthcare professional were analysed further. Data extracted and summarised from matching records included: number of records, date and time of contact, geographic location (and corresponding DHB) and healthcare setting (where applicable) of the person contacting the NPC, relationship of the person contacting the NPC to the patient, types of doctors (when and if documented; it is not a requirement to capture this information in the record), patient demographics (age, gender, Ministry of Health prioritised ethnicity[[16]]), reason for exposure incident and the number and identities of substances involved in exposure incidents. As patient age was not normally distributed, a median with an interquartile range (IQR) was calculated for the study sample. Therapeutic substances involved in these exposures were coded into WHO Anatomical Therapeutic Chemical (ATC) Classification System codes where applicable,[[17]] and non-therapeutic substances or products were classified according to the NPC in-house chemical classification system. The 20 most frequent therapeutic and non-therapeutic substances involved in these exposures were also determined. The total number of contacts made about human exposures for each study year was also determined to investigate time trends.

Results

During the study period, contacts relating to human patients exposed to various substances increased annually by 5.3–7.5%, whereas medical toxicologist consultations to healthcare professionals increased by 25.8–70.4% (Table 1). Of all 23,259 contacts relating to human patients in 2020, 1,526 (6.6%) involved toxicologist consultations.

A total of 3,451 medical toxicologist consults occurred during the study period, of which 2,614 occurred between 8 am and 7:59 pm (75.7%), while 837 occurred between 8 pm and 7:59 am (24.3%). The 3,451 contacts where NPC medical toxicologists were consulted resulted in 3,591 patient records (due to some exposure incidents involving more than one patient). A total of 2,400 records (66.8%) involved consultations with healthcare professionals contacting the NPC, while 1,191 (33.2%) involved consultations with NPC staff advising callers other than healthcare professionals. Of the 2,400 records involving consultations to healthcare professionals, 84.0% were to doctors (Table 2). When these were further analysed, 1,422 (70.6%) records indicated that the doctor was based in a hospital, 438 (21.7%) were in a medical centre, and 155 (7.7%) in other or unknown workplace settings. Table 2 summarises information about the types of doctors and other healthcare professionals who contacted the NPC.

Medical toxicologist consultations were provided to healthcare professionals from all DHBs. In proportion to DHB catchment area population size, Whanganui DHB had the highest rate of medical toxicologist-consulted records in 2020 (Table 3).

Among the 2,400 records, the median age of the patient was 25 years (IQR 13–48 years), patient ages ranged from 0 to 96 years, and 323 records (13.5%) had patients of unknown age. Patient ethnicities in these records were 12% Māori, 2% Pasifika, 2% Asian, 1% Middle Eastern/Latin American/African, 3% other ethnicity, 31% European (including New Zealand European) and 49% were of unknown ethnicity. A total of 951 of 2,400 records (39.6%) indicated that the exposure reason was intentional, and the rate was higher among females (52.9%) than males (26.4%; Table 4).

A total of 2,208 records (92.0%) indicated that the exposure was acute, while 192 (8.0%) were chronic exposures. The median number of substances involved in the exposure that were noted in the record was one (IQR 1–1; range 1–14); 1,764 of the 2,400 records (73.5%) had one substance involved, 302 (12.6%) had two, 147 (6.1%) had three, and 187 (7.8%) had four or more. There were 1,517 of 2,400 records (63.2%) that had at least one ATC-classifiable therapeutic substance involved in the exposure, while 883 (36.8%) did not and had only non-therapeutic substances. The 2,400 records contained a combined total of 3,788 substance exposures; 2,603 (68.7%) were therapeutic substances and 1,185 (31.3%) were non-therapeutic. Most of the therapeutic substances were from ATC groups N – Nervous system, and C – Cardiovascular system (Table 5).

Paracetamol was the most frequently consulted specific therapeutic substance in healthcare professional contacts with 528 of the total 2,603 therapeutic substance exposures (20.3%) involving paracetamol (Table 6). Ethanol was the most frequently encountered of all 1,185 non-therapeutic substance exposures, though mostly as a coingestant; it was the sole substance involved in an exposure in only 9 out of 114 records involving ethanol (Table 7).

View Tables 1–7.

Discussion

This retrospective study identified significant increases in annual numbers of consultations provided by NPC medical toxicologists. In 2017, prior to implementing a goal to increase links between the NPC and the broader clinical community, medical toxicologists provided a total of 253 consultations. During the study period, the number of consultations increased from 712 in 2018 to 1,526 in 2020. A quarter of NPC medical toxicologist consults occurred between 8 pm and 8 am, illustrating the importance of the service being available 24/7. There was use of the medical toxicologist consultation service from all DHBs. DHB catchment area populations were used to give comparison points for the number of toxicologist consultations to healthcare professionals in each DHB. Patients may have been exposed in or transported to another DHB for care, so these denominators are used simply as a means to compare numbers of consults in proportion to theoretical catchment area population numbers. The rates of consultation do not therefore indicate prevalence of poisoning. In proportion to area population size, less densely populated DHBs such as West Coast and Whanganui had higher rates of contacts compared to larger DHBs. This free access in any geographical area and at any time of the day or week can be used to promote health equity, as a specialist’s input can be used via telephone contact to optimise patient care.

Medical doctors of various scopes of practice and seniority (from house officers to specialist consultants) were the most frequent health professionals to consult NPC medical toxicologists. Although it was not possible to investigate medical specialties in this study, anecdotally most healthcare professionals requesting medical toxicologist consultation work in emergency departments, general practices or intensive care units. However, medical toxicologist consultations are also provided to a wide variety of other specialty fields including paediatrics, public health, internal medicine, gastroenterology, neurology, dermatology, general surgery, orthopaedics, etc.—emphasising how poisonings present in a large diversity of clinical scenarios. Consulting with an NPC medical toxicologist is similar to consulting any other specialist physician, although there is the limitation that the medical toxicologist cannot typically come to the patient’s bedside for an in-person evaluation. Clinicians seeking consultation are, however, given real-time advice relevant to the patient in front of them that includes practical considerations about ongoing management.

NPC enquiries typically involve young children (median age 3 years) with a “child exploratory” reason underlying the exposure.[[18]] In contrast, this study found that NPC medical toxicologist consultation exposures involved patients who were older with a median age of 25 years. Further, almost 40% of medical toxicologist-consulted records in this study involved intentional exposures, compared to a rate of only 5.5% observed in all NPC patient records in 2018.[[18]] An increase in rates of serious self-inflicted injuries including poisoning has been noted in Aotearoa New Zealand in recent years.[[19,20]] Intentional exposures often involve larger ingested doses not normally seen in unintentional exposures, multiple substances combined, undisclosed other substances and possibly delays in seeking treatment—which together introduce complexities in management and can result in serious morbidity and mortality.[[21–23]] The specialist expertise of medical toxicologists can be used to assist in such toxicologically complex cases.

Medical toxicologist consultations involved a wide range of different substances. Drugs primarily affecting the nervous system were the most commonly queried group of medicines in medical toxicologist consultations, similar to recent reports from Lebanon,[[24]] Singapore[[25]] and the United Kingdom (UK).[[26]] Paracetamol was the most frequent therapeutic substance in medical toxicologist consultations, similar to exposures reported to the NPC in general,[[18]] and in similar consultations of the UK’s National Poisons Information Service (NPIS) in 2020/2021.[[26]] Of note, the Australia and New Zealand guidelines on management of paracetamol poisoning encourage contact with medical toxicologists or poisons centres in several clinical scenarios, as written guidelines cannot cover all possible variations of circumstances.[[27]] As seen in Table 7, a wide variety of generally “uncommon” exposures (e.g., heavy metals, industrial chemicals) and exposures with public health implications (e.g., lead contamination, novel psychoactive substances) were advised on within the study period. The NPC is well placed to provide advice on rarely encountered clinical poisonings and to detect changing trends, e.g., in recreational drug use or intentional self-poisoning.

This study could not assess reasons why healthcare professionals sought consultation with a medical toxicologist, nor the value obtained. There are many reasons why a healthcare professional might desire consultation advice: medically complex patients or exposure scenarios, unfamiliar situations, uncertainty about management, multiple ingestions not easily addressed by existing protocols, evolution of new practice recommendations, newly emerging substances, advice on best practice or current evidence, etc. Value obtained from medical toxicologist consultation can be to the healthcare professional, the healthcare system and to the patient. Medical toxicologist advice can guide use of resources and interventions, including consulting on specific, complex interventions such as antidote use, decontamination strategies and extracorporeal elimination,[[28]] while also avoiding unnecessary, costly and even harmful interventions.[[9,13]] A recent study from the Netherlands found that 23% of hospital-admitted poisoning patients were retrospectively found not to require any active intervention.[[29]] Medical toxicologists can also advise on escalation of care if tertiary care in a larger facility is needed, or if other specialist input ought to be obtained. Further research is needed to determine healthcare professionals’ satisfaction with NPC medical toxicologist consultations, areas for further service development and ultimately whether there are measurable benefits to patients, e.g., in the form of shorter in-hospital and/or ICU stays, or to the health system in general in the form of cost savings, or others.

Limitations

Some limitations of this study should be noted. First, reasons for choosing to contact the NPC service beyond the need for obtaining toxicological patient management information were not determined in this retrospective record audit. Contacting the NPC is voluntary and therefore the data cannot be used to make any assessment of the prevalence of exposure rates in the community, as an unknown proportion of exposures are not reported to NPC. Some data, such as type and specialty of doctor, is not required to be captured in NPC records and thus a fuller description of the healthcare professional callers cannot be provided. Substance identities are recorded as reported by the person contacting the NPC and may contain inaccuracies or omissions, and in multi- as well as single-substance exposures all substances reported are counted in this study, regardless of whether they were of specific toxicological concern in the case. It is possible that population growth during the study period could have impacted the change in medical toxicologist consultations; between 2018–2020 the population of Aotearoa increased by 4%[[15]]—this factor alone is unlikely to explain the growth in medical toxicologist consultations. Lastly, NPC data do not systematically capture eventual outcomes for patients, and we are therefore unable to assess benefits to patients and/or treating clinicians from using the service in this study.

Conclusion

In summary, during 2018–2020 NPC medical toxicologists provided advice to medical professionals about various therapeutic and non-therapeutic substance exposures, and there was an increasing trend in the number of consultations over time across all areas of the country. These findings support the assertion that healthcare professionals across Aotearoa New Zealand derive value from this NPC specialist service and take advantage of 24/7 access to medical toxicologists from anywhere within the country. Moreover, the growth trend observed suggests further demand being present in the healthcare system for ongoing and continued development of the NPC’s medical toxicologist service. It is a priority for the NPC to develop its services further and continue to actively engage with the broader healthcare community.