But in the 2015 data, only 30 per cent of patients receiving clot-busting therapy got it within an hour of arrival to hospital.
"Earlier treatment is associated with better outcomes," the researchers say, "and every 15-minute acceleration in the start of treatment can result in a 4 per cent greater odds of walking independently on discharge."
A person arriving at hospital after hours would have faced a median wait of 82 minutes, "door to needle", to start the intravenous treatment - 13 minutes longer than the 69-minute wait during business hours.
The national all-hours median was 74.5 minutes, but times varied by region, from 69 minutes in the South Island, to 82 in Auckland-Northland. Larger district health boards may have been quicker than smaller ones and the hospitals with higher-tech "tertiary" services for stroke care - Auckland City, Waikato, Wellington, Christchurch and Dunedin - were faster, with a median of 67.5 minutes, than non-tertiary hospitals, on 81 minutes. The national median time from stroke onset to arrival at hospital was 72 minutes.
The researchers say the thrombolysis therapy rate of 6.4 per cent of patients meets the Health Ministry target of 6 per cent.
"This is similar to the national thrombolysis rate of 7 per cent in Australia (2012), but lower than 9.1 per cent in England (2011)."
Ranta indicated to the Herald specialists will support an increase to 8 per cent by 2018.
Stroke Foundation acting chief Don Scandrett said thrombolysis could be the difference between life and death, or between a positive recovery and permanent disability.
This was why the foundation had spearheaded the "FAST" campaign on recognising a stroke and calling 111.
Door-to-needle
Average time in minutes from arrival at hospital to start of clot-busting therapy
• 82 - Auckland-Northland
• 69.5 - Mid-North Island
• 74 - Lower North Island
• 69 - South Island
• 74.5 - All New Zealand
• 60 - Ideally the maximum
Source: NZ Medical Journal