She said Mr Tremain would have been unable to work here for months as he waited for an operation, missing out on thousands of dollars in income.
A doctor at Bragathi Hospital in Tamil Nadu, south India, told media Mr Tremain could not have had the surgery in private New Zealand hospitals because of high costs.
The doctor said Mr Tremain made contact with staff at Bragathi online before getting a hip replacement to tackle hip-joint arthritis.
The Business Standard website said Mr Tremain was the fourth New Zealand national to undergo hip replacement surgery at the hospital.
Ms Tremain said her brother was in Bali having a holiday after his treatment in India.
Despite evidence of Kiwis jetting abroad for treatment, the Ministry of Health said the average waiting time for New Zealand patients on the list for elective hip replacement had fallen from 72 days in 2010 to 41 days last year.
"More than 95 per cent of patients now receive their elective surgery within a maximum time of four months," said Dr Don Mackie, Ministry of Health chief medical officer.
He said the Government was committed to increasing elective surgery services, including hip and knee replacements.
"It is important that people carefully consider the benefits and risks of having surgery overseas," Dr Mackie said.
"The risks include a potentially increased risk of contracting infections such as Methicillin-resistant staphylococcus aureus (MRSA), and possible complications around any post-operative care needed in New Zealand."
He said there'd always be variation between the cost of surgery in different countries.
Dr Mackie said much of the cost of surgery here was from labour costs as New Zealand provided "a highly skilled work force."
He said the price of equipment, implants, and follow-up care could also impact surgery costs here.
Dr Mackie said 162,169 people had publicly-funded elective surgery in the 2013/2014 year.
Only 117,959 people had such surgery in 2007/08.
He said 10,775 people received hip and knee replacements last year, up from 8,503 in 2007.
Dr Mackie said a new programme aimed to create "multi-disciplinary early intervention teams" to help people experiencing painful musculoskeletal conditions.
"There are a lot of people with osteoarthritis, for whom early intervention and conservative management in a primary or community setting is appropriate," he added.
"Early intervention can deliver improvements in diagnosis, self-management, education and exercise, weight management, pain management and support prevention strategies."
- NZME
