I had the right to remain silent, but I cannot. A report purporting to be "science" slanders the global community of surgeons in the current issue of The Lancet, and I am trying to choose my words and tone carefully because I am afraid my head will explode.
Entitled “Deaths within 30 days of surgery in low, middle-, and high-income countries,” it asks what might the quality of surgery be like globally when based on the standard 30-day post-operative death rate. While post-operative death is a component of quality, it is certainly not the only measure although the unfortunate patients that die might disagree. The heavy lifting of the extrapolation and guesstimation in their conclusions comes from the fact they acknowledge in the 3rd line of the opening paragraph, “robust postoperative death rates are available for only 29 countries.”
To calculate post-operative deaths, they considered the number of patients having surgery, the rate of post-operative deaths, and the mix of sick and well patients (case-mix). Their mathemagic lies in determining those numbers for the global surgical community. Here is what they say, “total operations performed… are not readily available… there are no readily available LMIC (lower and middle-income countries) national surgical registries to estimate LMIC case-mix…;” To determine the rate of post-operative deaths they chose one high-income country, the UK, and then extrapolated based on per capita spending on health care.  Oh yes, because they had no complete mortality data but did have studies showing higher mortality in those LMIC countries, they also adjusted the mortality upwards, using a "morbidity constant."
But perhaps channeling the surgery they were defaming they buried the acknowledgment and rationale for their mathemagical choices deep within the supplement - a document at least four times as long as the 2-page report. But here is, the red meat, as it were, of their calculations.
“Overall, our analysis suggests that currently at least 4.2 million people around the world die within 30 days of surgery each year, with half of these deaths occurring in LMICs. We project that expanding surgical services to address unmet need would increase total deaths to 6.1 million annually, with an additional 1.9 million occurring in LMICs each year. Based on 4.2 million deaths, 7.7% of all deaths globally occur within 30 days of surgery. This figure is greater than that attributed to any other cause of death globally except ischaemic heart disease and stroke. More people die within 30 days of surgery than the combined 2.97 million deaths attributed to HIV, malaria, and tuberculosis annually.” (emphasis added)
That last statistic is frightening; but did you notice any word about the lives surgery saves. The premise is that 143 million people need surgery they cannot currently access. So how about throwing us a bone and at least say that while there will be an increase in postoperative deaths, we would have helped the other 137 million people.
They "walk back" their words, once again deep in the supplemental appendicies with this disclaimer,
“…we do not seek to imply causality between patients undergoing surgery and dying within 30 days. Some postoperative deaths may be entirely unrelated to the patient’s surgery, for example, deaths resulting from trauma. For some patients postoperative death represents a failure of surgery as a treatment strategy; for instance, a patient who succumbs despite attempted surgery for a ruptured abdominal aortic aneurysm.”
The real number of preventable deaths, those from surgical complications is unknown. This article provides no light and serves up only shade, denigrating dedicated physicians who “don’t let the skin get between them and a problem.” Surgery carries risks; every surgeon knows that in ways far more personal than any of this “report” suggests.
Leave aside the fuzzy math, the purpose of emphasizing the deaths and not the lives saved is to attract eyeballs. Let me end with another quote from the Lancet 
“Our interests are best expressed in the material we publish rather than in any pretentious mission statement fashioned from the thesaurus of a management course.”
Is this report really your interest?
 The UK's overall post-operative death rate for 14 specialties was 1.09% - roughly 38,000 out of 3.4 million.
 Lancet editorial "Goodbye to all of that"
Source: Deaths within 30 days of surgery in low-, middle-, and high-income countries The Lancet DOI: 10.1016/S0140-6736(18)33139-8