ANALYSIS: ‘Close to a million’ smokers quit under South Africa’s Covid-19 rules? Limits to lockdown research
The first phase of South Africa’s Covid-19 lockdown, introduced in late March 2020, put strict limits on what people could do. They could only leave home to get medical care, buy groceries and collect social grants. The sale of tobacco and alcohol was banned.
The rules have since been relaxed to allow alcohol sales, but the tobacco ban remains – and remains controversial. More than half a million people have signed a petition to repeal it, and a tobacco lobby group has taken the government to court.
“Close to a million people stopped smoking during the lockdown,” Savera Kalideen from the National Council Against Smoking says in the clip. Kalideen tweeted a similar claim a few hours after the health department posted its video. (Note: The department’s tweet gives Kalideen’s title as “Dr”. She told Africa Check she is not a doctor.)
Given the public health implications of such a significant shift, we took a closer look at how the number was estimated.
16% of smokers stopped smoking during the lockdown according to REEP Survey. They estimated this to be between 800 000 and a million smokers who chose to stop. https://t.co/YPgxfFZ86v
— Savera Kalideen (@SaveraKalideen) June 1, 2020
Online survey with free stuff incentive
Kalideen said an online survey by the Research Unit on the Economics of Excisable Products (Reep) at the University of Cape Town (UCT) found that an estimated 800,000 to a million smokers had chosen to end the habit under the ban.
The survey, conducted in April and May 2020, was anonymously completed by more than 16,000 people. Reep analysed 12,204 answers. A chance to win one of 10 retail vouchers was offered as an incentive to complete the survey.
The results were weighted to be “as reflective of the smoking population as possible”.
The report adds that because it was a survey of cigarette smokers, this “population” is not South Africa’s entire population as counted in the most recent census, but the population of smokers.
Percentage to number?
The survey report estimates that “16% of smokers at the start of the lockdown were able to quit successfully”.
Is this “close to a million people”, as Kalideen claims in the video? The report does not include this number – or any number for people who have quit smoking under the ban.
But it estimates that before the ban, 6.5 million adults in South Africa regularly smoked cigarettes. The figure was calculated using UCT’s most recent National Income Dynamics Study. This national multi-year survey is designed to track poverty, household dynamics, livelihood and other social factors.
A National Council Against Smoking spokesperson told Africa Check how they had calculated the number.
Sixteen percent of 6.5 million “is 1,040,000”, they said. “Thus it is a safe estimate that 800,000 to 1 million smokers above 18 have stopped smoking.”
Reep’s director, Prof Corné van Walbeek, told us the calculation was acceptable. Kalideen “quoted our study and we stand with this percentage”, he said. “The arithmetic is fine too.”
Smoking and selection bias
But selection bias could be a concern for a survey like this, Dr Maia Lesosky, associate professor of epidemiology and biostatistics at UCT, told Africa Check. “People who are particularly interested in the topic tend to be more willing to complete the survey than a random sample,” she said.
“The larger the survey and the more diverse a community the survey reaches, the better.”
The researchers noted that their questionnaire was “likely to be completed by more affluent and connected people”.
‘Worst possible outcome’?
Another possible hurdle was people self-reporting their smoking status. The survey asked: “Have you successfully quit smoking over lockdown?” No definition of what “successfully” quitting meant was given.
Many studies of the process of quitting smoking require more of participants than simply saying they have quit. Their self-reported status is also tested to determine if their bodies contain evidence of recent tobacco use.
Van Zyl-Smit said it could have been difficult to test people’s self-confirmed smoking status during the lockdown.
Survey numbers ‘almost certainly’ overstated
The survey “almost certainly overstates the number of people who have really quit”, said Prof Charles Wheelan, a senior lecturer at Dartmouth College in the United States and author of Naked Statistics and other books.
Wheelan, who also flagged the challenge of selection bias, said survey takers “are likely to overstate their ‘success’ in quitting”.
“We know how hard that can be.”
A 2009 report analysing 72 studies of methods to quit smoking during pregnancy found that “misclassification of smoking status by self-report” was “one of the most significant risks of bias”.
Stopping and starting
It’s possible that people who quit smoking during the lockdown will resume the habit when the ban is lifted. The Reep report estimates that 12% of quitters plan to start again.
Dr Evan Blecher, an economist in fiscal policies for health at the World Health Organization, told Africa Check that smoking relapse rates were high.
“That is why many studies that attempt to measure the effectiveness of cessation methods look at cessation rates at intervals of years.”
“How many will go back to smoking is hard to guess, but I would suspect it’ll be a high number, especially without support programmes.”
Lesosky concurred that when the lockdown ended and people returned to their usual routine, many of South Africa’s new ex-smokers might find it difficult to continue to abstain.
“I don't think this has anything to do with the survey though, or with the nature of the survey. It’s just the reality of how difficult it is to manage a smoking addiction.”
The researchers themselves noted “several other weaknesses and caveats” with their survey. Some survey takers might not have answered truthfully due to fear of being caught, for example. Other issues were the stigma of smoking and the timing of the study.
Bottom line? Lockdown made it easier for many to quit
To establish if the wholesale quitting was a short-term trend or not, Kalideen said, more research was needed. Reep is currently conducting a second survey on the effect of the ban on smoking.
But despite the survey’s shortcomings, there was “significance to the overarching point that the lockdown has made it easier for many people to quit smoking”, Wheelan told Africa Check.
“Even if the numbers are overstated, it still means that making tobacco products less accessible is likely to reduce smoking rates.”
Nonetheless, the survey calls for the ban to be lifted. “People are buying cigarettes in large quantities, despite the lockdown,” it says. These are increasingly of the illicit variety, on which the full amount of taxes have not been paid.
The debate continues to smoulder.