The Martha’s Vineyard Hospital has been identified as one of the most expensive in Massachusetts in data compiled by one of the state’s major health insurers.

The numbers, from Harvard Pilgrim Health Care, given this week before the start of state hearings into the rising costs of health care, found the Vineyard Hospital ranked number five among 72 hospitals in the state. Nantucket Hospital which, like the Vineyard hospital, is part of the Partners Healthcare network, ranked third.

The insurance data, from Harvard Pilgrim and several other big insurers, forms the backdrop to a report also released this week by the state attorney general’s office, analyzing the factors driving up health costs.

That report found that the costs billed to insurers by various hospitals varied widely, and bore no relation to the quality of care offered by hospitals. Nor were they related to the sickness or complexity of the population being served by the hospitals, nor whether they dealt with large numbers of Medicare or Medicaid patients, nor whether they were major teaching hospitals or research facilities.

Instead, the report found, the price differences were correlated to “market leverage” — in essence what they could charge because of their geographic location or the power of, or within, a group of medical providers.

“Wide variations in price are unexplained by differences in quality of care as measured by the insurers themselves,” the attorney general’s report says.

“We compared price and quality data using dozens of graphs and statistical calculations to determine whether there is a correlation between price paid and quality measured. Our results indicate that there is no correlation between price and quality, and certainly not the positive correlation between price and quality we would expect to see in a rational, value-based health care market.”

The disparities in hospital prices were not explained by hospital costs either, the report found.

“We reviewed information showing wide variations in hospital costs that appear to track the amount the hospitals are paid rather than the acuity, complexity or quality of the hospital’s services,” it says.

“Our analysis suggests that hospitals may manage costs, including capital expenditures, to budgets based on their anticipated revenue from insurers and any other sources of income.”

From a cost-control perspective, the report found that the more expensive hospitals were gaining market share, while the less expensive ones were losing it.

And that came down to what the authors called “leverage.”

“We define ‘leverage’ as a measure of the ability to influence the other side during negotiations,” the report says. “Typically, leverage results from variables such as: size, geographic location, ‘brand name.’”

Yet the largest and most prestigious hospitals were not always among the most expensive, although the reimbursement varied for different insurers.

The Harvard Pilgrim data showed the highest reimbursements went to Fairview Hospital in Great Barrington, followed by Dana-Farber Cancer Institute, Partners Nantucket Cottage, Children’s Hospital, Boston Children’s Hospital and Partners Martha’s Vineyard.

The two largest hospitals in the Partners HealthCare group, Massachusetts General and Brigham and Women’s, came in 12th and 18th respectively.

Overall and across all the insurers surveyed, however, Partners affiliates tended to be among the most expensive, with their smaller hospitals consistently at the more expensive end of the table.

The mystery of why the Vineyard hospital was so expensive was not explained by the analysis of factors which might reasonably be thought to drive costs up.

The report showed it did not deal with a particularly unhealthy population. Nor did it have an unusually high number of Medicare/Medicaid patients. It does not bear the costs associated with being a major teaching or research facility.

And although the report did not look specifically at capital costs, the Vineyard hospital is in a good position there, too; the cost of building a new hospital having been met by donations.

The Gazette sought comment from the hospital’s president and chief executive, Tim Walsh, but had received no response late yesterday.

The latest data is not the first instance in which costs at the Vineyard hospital have been shown to be unusually high.

Last July, an analysis by the Gazette of figures collated by the state Division of Health Policy and Finance on insurance payments for outpatient medical procedures showed the Vineyard hospital to be vastly more expensive for outpatient services than the median across the state. In most cases the cost here was double, or more.

To cite one outstanding example, an ultrasound for a woman in the first three months of pregnancy cost $800 here, compared with $100 at the nearby Falmouth, St. Luke’s and Tobey hospitals on the mainland.

In response to those numbers, Mr. Walsh said the higher charges here reflected higher costs. The Medicare wage index showed the Cape and Islands were 30 per cent above the state average. Also, the seasonal nature of the Island meant services were provided that were not always fully utilized.