Nearly six in 10 deaths from treatable conditions in low- and middle-income countries result from low-quality healthcare -- a bigger killer than insufficient access to treatment, researchers said Wednesday. 

Every year, about five million people in these countries die as a result of sub-standard care, according to a report published by The Lancet medical journal.

This was out of 8.6 million total deaths from treatable conditions, and far outweighs the 3.6 million deaths from lack of access to healthcare. 

Overall, deaths from treatable conditions cost the global economy some $6 trillion (5.2 trillion euros) in 2015 alone, the researchers found, pointing to "systematic deficits" in primary and hospital care. 

"For too long, the global health discourse has been focused on improving access to care without sufficient emphasis on high-quality care," said Muhammad Pate, a co-author of the report by The Lancet Global Health Commission, of which he is co-chairman.

"Providing health services without guaranteeing a minimum level of quality is ineffective, wasteful and unethical," he said, and warned there was a "vast epidemic of low-quality care."

Substandard care was a factor in 84 percent of cardiovascular deaths, 81 percent of vaccine-preventable diseases, and 61 percent of post-birth complications. 

Typically, mothers and children in low- and middle-income countries received less than half the recommended interventions -- including blood pressure monitoring during birth, and newborn checkups.

Less than half of suspected tuberculosis cases were correctly managed, and fewer than one in 10 people with a major depressive disorder received even minimally adequate treatment, the report said.

"Diagnoses are frequently incorrect for serious conditions" such as pneumonia, heart attacks, or newborn asphyxia, a condition that can cause death by suffocation, it added.

"Care can be too slow for conditions that require timely action, reducing chances of survival."

Among women receiving medical care during pregnancy, the wealthiest were four times more likely to have urine and blood tests done, and to have their blood pressure monitored. 

The highest toll was in India, where substandard healthcare was responsible for an estimated 1.6 million deaths a year, the researchers said.

"Quality care should not be the purview of the elite, or an aspiration for some distant future; it should be the DNA of all health systems," said commission co-chair Margaret Kruk of the Harvard T.H. Chan School of Public Health.

"Countries will know they are on the way towards high-quality, accountable health systems when health workers and policymakers choose to receive health care in their own public institutions."