Gifts and payments to US doctors from drug firms are seen by some as encouraging unnecessary prescriptions. Do such transfers make any difference and will President Obama's healthcare reform help, by forcing companies to disclose them?
Prescribe enough drugs and - as detailed in 1974 Senate hearings - a doctor could accumulate points to exchange for a wide range of consumer desirables - colour TVs, watches, microwave ovens, lawnmowers, golf clubs.
The hearings were part of a campaign led by Democratic Senator Edward Kennedy, and exposed a culture that, since the 1950s, had become pervasive.
In the decades that followed, the pharmaceutical industry grew and the stakes got bigger. As more information about doctors' prescribing habits became available, more money was spent trying to influence them.
The 1990s saw the release of a number of "blockbuster" drugs, and were seen as boom years for the drug "reps" who act as intermediaries between doctors and industry, handing out samples of products and deploying a variety of studied tactics to boost both company profits and their own salaries.
Michael Oldani, who worked as a rep for Pfizer before becoming a medical anthropologist, has described how offering food and drink - free bagels, lunches and coffee coupons - was a favourite strategy.
Gifts could range from pens to bottles of wine to "unrestricted educational grants" worth thousands of dollars. "We did all sorts of crazy stuff in the industry," Oldani says. "The regulation hadn't caught up with us."
The gradual exposure of such practices by whistleblowers, prosecutors and the media eventually led to a series of professional and industry guidelines, targeting some of the most flagrant financial transfers. Cash inducements were made illegal in some states, and outlawed federally for prescriptions covered by the Medicare and Medicaid programmes.
These measures, along with what many observers say has been a shift in culture, appear to have made some difference.
But doctors may still be paid for public speaking and consultancy or given funds for medical education or research.
A study by Eric Campbell of Harvard Medical School found that among a random sample of doctors, the share of those who said they had received gifts from industry fell from 83% in 2004 to 71% in 2009. The share for those acknowledging payments for services such as consulting or public speaking dropped from 28% to 14% over the same period.
Even in 2009, however, nearly 84% of respondents reported a relationship with industry. As Campbell says, "still the vast, vast majority of physicians are getting things from drug companies".
Some relationships have led to illegal behaviour. Top pharmaceutical companies have reached settlements with the Department of Justice totalling tens of billions of dollars over allegedly fraudulent marketing of drugs, sometimes through payments to doctors.
But most transactions fall within what is professionally and legally permitted, and supporters defend them as helping the best new treatments reach people who need them.
There is "great value" in exchanges of information between healthcare sector and industry, says Kendra Martello, a deputy vice-president at PhRMA, which represents leading pharmaceutical companies. "Better educated physicians provide better care to patients, in my view."
Tom Stossel, a doctor and a professor of medicine at Harvard, says medicine is "incomparably better" today than it was 50 years ago, and that "all of this is thanks to the tools that physicians have gotten from industry".
He discounts claims that payments have distorted decision making as "speculation", says drug firms only settled to avoid being barred from government contracts, and calls criticism "mean spirited, holier-than-thou stuff".
"Doctors could go to a restaurant, learn something, get a nice dinner - what was wrong with that? Is education better in a monastery than in a restaurant?"
It is hard to track payments over time, or to measure their impact.
However, critics say there is evidence that they affect prescribing habits, and that this drives up costs and health risks.
A recent study by three US economists found that a doctor receiving payments from a pharmaceutical firm was more than twice as likely to prescribe its drugs, compared to doctors receiving no payments.
Using data from more than 330,000 doctors and 12 pharmaceutical firms, it identified 58% as having received payments. It found that payments were unlikely to represent significant opportunities to educate doctors about new drugs, and that financial gain appears to be an important motive for doctors.
Daniel Carlat, director of the prescription project at the non-profit group Pew Trusts, says research to date shows that doctors who have dealings with drugs reps "tend to prescribe differently".
"They prescribe more drugs, more expensive drugs, more brand-name drugs, and they're less likely to follow evidence-based practice guidelines in prescribing drugs.
"To the extent that all of those relationships lead to inappropriate prescribing... that could be a massive problem in terms of healthcare costs and also in terms of public health."
Payments and gifts can result in individual doctors switching their "obligation" from the patient to the drug company, argues Oldani. On a general level, he says, they have fostered a "drugs first mentality" in which doctors prescribe too readily, at the expense of therapy or other treatments.
It is in this context that "blockbuster" drugs have flourished, in the US and beyond.
"The reason that there's so much heavy marketing is that the vast majority of these 'new drugs' are out there are pretty much similar to what already exists on the market," says Campbell.
"If drug companies make drugs that really work, doctors will use them. They don't have to pay doctors to know about them, they don't have to pay doctors to use them."
In terms of health risks, there is concern that payments can compromise the process of bringing a drug to market, and that once a drug is approved, they can encourage excessive or "off-label" use.
Oldani has written about an antibiotic that his company aggressively marketed, but which was restricted by the Food and Drug Administration shortly after its use because of its association with liver toxicity, and in severe cases, death: "Gifts included pens, clocks, free dinners, symposia with expert speakers, and post-marketing clinical grants, all of which went toward accelerating prescription growth and eventually led to severe side effects."
Pfizer said in a statement that it used training and monitoring to comply with the law, and partnered with doctors "to educate other health care providers regarding important safety and effectiveness information".
"Pfizer is committed to fairly compensating health care professionals, clinical investigators and research institutions for the work they do to advance human health and patient care," the statement said.
"This epidemic began in the late 1990s in response to a pharmaceutical industry-funded campaign that led the medical community to believe that opioids were safe and effective for very common chronic conditions," says Andrew Kolodny, chief medical officer at Phoenix House, which works to help drug abusers.
Influential doctors paid by industry headed "professional societies that issued consensus statement calling for aggressive prescribing", he says.
While no-one has quantified the overall financial and health-related consequences of payments, concern over conflicts of interest led to a push for disclosure in the US.
Later this year, under a little-known provision of President Barack Obama's healthcare reform called the Sunshine Act, industry payments to doctors will be published on a public website.
The measure may already be having an impact. Research by Pro Publica, an investigative news organisation, recently showed that some of the biggest pharmaceutical firms had dramatically scaled back payments for promotional talks.
And British firm GlaxoSmithKline - which in its efforts to boost prescriptions was recently accused of bribing doctors in China and paying state-employed doctors to work as sales reps in Iraq - announced in December that it would stop paying physicians to promote its drugs, while also decoupling compensation for reps from the number of prescriptions written.
PhRMA is concerned that the Sunshine Act may have a "chilling effect" on the exchange of information, saying some doctors are refusing medical article reprints from drug reps because these can be seen as "transfers of value".
But experts say drug firms may be spending less because they have fewer expensive, patented products coming on to the market.
And industry critics worry that the Sunshine Act could simply legitimise payments, that companies may spend more on marketing directly to patients, and that despite guidelines and firewalls they may still be able to steer medical practice using funds labelled for education or research. Spending may shift to more unregulated markets in the developing world.
"There's a lot more money now and there's a lot more sophistication about how to influence judgement, and this is being deployed," says Marc Rodwin, a law professor who has written about conflicts of interest in medicine in the US, France and Japan.
"There's basically a financial impetus that's going to push for this kind of activity unless it's made illegal."
Arthur Caplan, head of medical ethics at New York University, says that impetus will endure in the US as long as it relies on a market model, instead of the large government purchases used in Europe that drive down the cost of drugs.
He thinks that faced with the prospect of payments being disclosed, "most doctors will stop" taking them, though more through pressure from peers than from patients.
But, he adds, as pharmaceutical firms "shift to marketing to the patients and lobbying, they can easily make it up".