Friday, 22 June 2018

Alcohol healthwatch - again

"One-third of NZ's hazardous drinkers are now aged 35-54," says Alcohol Healthwatch executive director Dr Nicki Jackson.

"For the older groups, hazardous drinking is now higher than it was back in 2006/07. It feels like we have a new 'peak booze' among parts of our population."

The Ministry of Health estimates that over 780,000 adults are hazardous drinkers. Statistics NZ figures show the drinking habits for more than a third of people aged 18-24 could be potentially hazardous - regularly consuming six more drinks in a single session.

Dr Jackson warns there's been an increase in hazardous drinking every year since 2011, and says it's increased by more than 50 percent among those aged 45 to 64 years.

As well as this, hazardous drinking in the 66-74-year age group more than doubled from 2011/12 to 2015/16.

"Our older drinkers are some of the heaviest drinkers in the world," she says.
Let's go back to the stats.

The 2015/16 New Zealand Health Survey does have an increased prevalence of harmful drinking (AUDIT score 8 or higher) for total population in each year from 2011/12 through 2015/16. But that came after a substantial drop from 2006/07. So the 2015/16 figure is now a bit higher than it was in 06/07. The rise from 11/12 to 15/16 is statistically significant, but there is no significant difference between 05/06 and 11/12.

While 32.6% of those aged 18-24 were considered hazardous drinkers by that standard in 2015/16, 43.2% were considered hazardous drinkers in 2006/07. It's been flat on "about a third" since 2011/12. The drop from 06/07 to present is significant; there's been no significant change though since 2011/12.

There were statistically and real-world significant drops in the prevalence of hazardous drinking from 06/07 to 15/16 for cohorts under the age of 24. Prevalence among 15-17 year olds roughly halved (19.5% to 11.5%); among those aged 18-24, it dropped by about a quarter (43.2% to 32.6%).

There was no statistically significant change over the period for those aged 25-34 (though higher now than before, with a large rise from 14/15 to 15/16), or for the 75+ cohort (which dropped from 3.6% to 2.9%).

There were statistically significant increases in prevalence from 06/07 through 15/16 for 35-44 year olds (16.6% to 22.3%), for 45-54 year olds (12.2% to 18.5%), and for 65-74 year olds (7.3% to 10%).

So if you want to tell a story about big increases in rates, you can pull out the 06/07 data and start from 11/12, which seems the bottom of a trough, or ignore what's been happening for younger cohorts, or both. The Ministry of Health data only goes back to 06/07, but overall per capita consumption data has a massive drop from 1987 to 1997, a mild rise through 2010, then a fall through present. If overall hazardous drinking is up 2011/12 through 2014/15 despite a drop in per capita consumption, then maybe whatever the government's doing on alcohol policy is doing more to deter moderate drinkers than it is doing to affect heavier drinkers.

It's also worth looking at the other measures in that survey.

MoH tallies the proportion of people consuming 6+ drinks on one occasion at least monthly. That figure is statistically significantly down overall from 06/07 through 15/16 (22.5% to 19.3%), massively down among 15-17 year olds (25% to 9.4%), and also down for 25-34 year olds (30.7% to 26.3%).

The only statistically significant change for any other subgroups were an increase among Maori women from 2011/12 through 2015/16 (23.4 to 27.8% but as the 2006/07 proportion was 28.0%, there was no change over the longer period), and smallish drops among European men and Europeans overall.

If you flip to the "Consumption of 6+ drinks on one occasion at least weekly" figure, you get a significant drop overall, a significant drop among men, and significant drops in the under-24 age cohorts.

It's also worth checking the most recent figures.

Again, the new ones aren't commensurable with the older ones, so we only have the change from 15/16 to 16/17. The proportion of hazardous drinkers dropped from 20.8% to 19.5% in the total population, and from 26.2% to 24.7% among past year drinkers. Heavy episodic drinking at least monthly is up by fractions of a percent, but heavy episodic drinking at least weekly is down fractions of a percent. None of those changes are worth noticing, but the drop in the most recent year contrasts with Alcohol Healthwatch's "there's been an increase in hazardous drinking every year since 2011".

Anyway, your regular health warning about relying on Alcohol Healthwatch's stats applies. It's usually worth going back and checking the original data yourself to see what's been left out.

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