Harmonized Work Health and Safety Laws and Traumatic Occupational Digit Amputation in Australia: A Staggered Difference-in-Differences Study

Has WHS harmonisation impacted traumatic digit amputation rates?

This new study statistically analysed the 2012/13 WHS harmonised adoption cohorts vs Victoria (non-harmonised) to evaluate any impacts from harmonisation.

Note – IRR = incidence-rate ratio (IRR). It’s a way to express a relative difference between two groups, where 1 is no difference, 1.2 is 20% higher or 0.8 is 20% lower etc.

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Extracts:

·       “Traumatic amputation of the fingers or thumb is a common, disabling, and mechanistically well-understood form of occupational hand trauma”

·       Some global data modelling suggests 1.86 million thumb amputations & 4.3 million non-thumb digit amputations worldwide in 2017 alone

·       The author “found no evidence that harmonizing WHS laws was associated with reduced accepted workers’ compensation claims for digit amputation among the primary adoption cohorts”

·       Namely, the “primary IRR was 1.03 (descriptive 95% CI: 0.85-1.25) across all jurisdictions and 1.00 (0.83-1.20) excluding NSW, with no evidence of an association under exact randomization inference (RI-β p = 0.89 overall and p = 0.98 excluding NSW)”

·       It’s argued that perhaps “One possible interpretation is that harmonization occurred against an already-declining and already regulated hazard, leaving limited additional room for measurable reductions attributable to the reform”

·       E.g. harmonisation wasn’t introduced into the wild west – an existing legal framework was also in place

·       And “Digit amputation was also already declining. Victoria never adopted the model WHS laws, yet its own age standardized hospital admission rate for work-related digit amputation fell from 12.54 to 4.71 per 100,000 employed persons between 2005/06 and 2022/23”

·       “Machinery-related outcomes were likewise null (IRR: 0.99, p = 0.96; broader time-loss IRR: 0.99, p = 0.80)”

·       The author notes that this doesn’t indicate that regulation is ineffective (at least on claims data), but it had limited statistical power to detect only a modest effect

As always several limitations which are described in the article.

Study link: https://www.cureus.com/articles/541472-harmonized-work-health-and-safety-laws-and-traumatic-occupational-digit-amputation-in-australia-a-staggered-difference-in-differences-study#!/

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