Patients with dyspnoea transported by ambulance to hospital have a high morbidity and mortality from respiratory diseases , a Victorian study shows.

One in every seven Australian patients who call for an ambulance are exhibiting breathlessness when crews arrive, the analysis of emergency service data has shown.

Researchers says the finding highlights the need for a greater focus on emergency care of patients with dyspnoea, with 30-day mortality rates of 9% of those assessed by paramedics as meeting inclusion criteria for the condition.

The study of Ambulance Victoria records in the five years to June 2019 showed that the most common final diagnoses were lower respiratory tract infection (13%), COPD (13%),  heart failure (9.1%), arrhythmias (3.9%), acute coronary syndromes (3.9%) and asthma (3.2%).

Among the most common diagnoses, STEMI had the worst prognosis with a 30-day mortality of 14.3%, followed by 10.9% for lower respiratory tract infection.

Other high mortality diagnoses were heart failure (9.8%), NSTEACS (8.3%), non-AF arrhythmias (6.9%) and COPD (6.4%).

Predictors of mortality included older age, male sex, pre-existing chronic kidney disease, heart failure or cancer, abnormal respiratory status or vital signs and pre-hospital intubation, reported the researchers led by Dr Jennifer Zhou, a cardiology registrar at Alfred Health in Melbourne.

All up, there were 345,228 callouts for patients experiencing respiratory problems over the study period, representing 14% of the total.

The researchers were able to link just over 271,000 of these patients with hospital and mortality records, finding 79% of required hospital admission.

Other findings included that inhaled bronchodilators were frequently used, corresponding to high rates of asthma and COPD, while cardiac interventions such as nitrates and aspirin were also common.

Notably, only 2.3% of patients were treated with pre-hospital non-invasive ventilation (NIV) in the study, despite some secondary data indicating its use reduced the need for intubation and improved survival, the researchers noted.

“While these data should be recognised as exploratory, it is possible that the pre-hospital application of NIV in patients with respiratory distress may represent a target to improve outcomes,” they wrote in Emergency Medicine Australasia.

Antibiotics were also used in only 0.04% of cases, despite high rates of lower respiratory tract infection and sepsis. However, the researchers speculated this was possibly due to the fact that antibiotics were not currently a routine part of Ambulance Victoria’s treatment protocols for sepsis.

It follows research published last year finding about 10% of Australian adults reported clinically important levels of breathlessness.

Based on a survey of 10,000 adults conducted in 2019, the industry-funded study also found half of those experiencing breathlessness did not report a current respiratory or heart condition diagnosis.

Of the breathless group, half rated their general health as fair or poor and 44% had depression or anxiety symptoms.