When Atul Gawande's book Being Mortal came out in the autumn of 2014, the marketing department at his American publisher expressed some concern; it wasn't exactly upbeat. The subject matter was clearly signalled in the subtitle: Illness, Medicine and What Matters in the End. Who, in the holiday season, would want to read a book about dying?

As it turns out, a great many people (including United States President Barack Obama, who was seen buying it in a Washington bookstore shortly after publication). Not only that: to the publisher's, and writer's, surprise, it was being bought as a gift. People were purchasing several copies and giving them to families and friends. The book immediately leapt into The New York Times bestseller list, where it remains; within two months its sales had exceeded the combined total of Gawande's previous medically related works, Complications (2002), Better (2007) and The Checklist Manifesto (2009).

Gawande, who is a surgeon and a writer for The New Yorker magazine, is addressing a global conundrum. We're all living longer but the quality of our lengthened existence is in many cases diminished. As he puts it in Being Mortal, "The waning days of our lives are given over to treatments that addle our brains and sap our bodies for a sliver's chance of benefit." Dispatches from those at the front are rarely encouraging. He quotes American writer Philip Roth, from his novel Everyman: "Old age is not a battle. Old age is a massacre."

In 2009, Gawande began exploring this final journey - the one some of his patients, both young and old, have had to undertake - with a sense of frustration and curiosity. He, a medical man, had no useful maps to give them as they painfully crossed mortality's frontier. Along the way, he interviewed more than 200 patients and their family members, and spoke to dozens of people involved in every aspect of care-giving in hospices, care-homes, assisted-living communities.

He did statistical research, much of it to do with the elderly: in the US today, there are as many 50-year-olds as there are five-year-olds but, between 1996 and 2010, the number of certified geriatricians in practice fell by 25 per cent. He delved into history. "Nursing homes" were originally built to house impoverished sick people who had nowhere else to go. They weren't intended to be the ultimate destination for a nation's senior citizens.

Most of all, he found individual stories he could tell. He describes the final years of Alice, his grandmother-in-law in Virginia, whom he met when she was in her late 70s. Her decline from being an independent, lawn-mowing, plumbing-fixing, life-affirming spirit to a woman effectively incarcerated in a (well-organised, well-meaning and - crucially, for her family - safe) home is conveyed with wince-inducing clarity. For Alice, life becomes no longer worth living. One April evening, in the room she shares with a stranger, she fleetingly mentions her abdominal pain to a nurse. Then she decides to say nothing more - to endure silently until death releases her in the night.

In the course of his research, Gawande's father developed a spinal tumour; and so his wide-ranging, isn't-this-interesting, academic journey circled back to his parents' doorstep, in Ohio, and narrowed to the personal. "I'm afraid, Atul," his father, himself a doctor, told his son.

That son - a Stanford graduate, a Rhodes scholar at Oxford, an alumnus of Harvard Medical School, a man already listed in Time magazine as one of the world's most influential thinkers - then had to ask "with great trepidation" some of the hardest questions of his life. He had to find out his father's fears, the physical trade-offs his father was prepared to accept in order to live longer, what it was that defined the quality of his father's life.

Beforehand, as he writes, he'd feared "I don't know what - anger from my father or mother, depression, or the sense that just by raising such questions I was letting them down. But what we felt afterward [ sic] was relief. We felt clarity." Communication, he'd learned from the palliative-care experts, was crucial. In the end, his father died at home, with his family.

Many books have been written about dying. Not many of their authors, however, can remark from experience, as Gawande does: "When you reach inside an elderly patient during surgery, the aorta and other major vessels can feel crunchy under your fingers." (Calcium deposits, apparently.) Gawande's background - intellectually accomplished, emotionally attuned - gives his quest a unique perspective. That's why people, at a certain stage in their own lives, want to know what he has to say.

In a 2014 interview with a Calcutta newspaper, Gawande mentions that he gets 2,500 speaker-invitations per year, a number that can only have increased.

In November, he was in Hong Kong to speak at an Asia Society lunch; to speak to the Harvard Club of Hong Kong; to speak to the Hong Kong Academy of Medicine; and to be interviewed by several journalists from the Chinese press about the (traditional) Chinese edition of the book that had just come out. He was also having meetings about Hong Kong's public health system.

THIS IS GAWANDE'S first visit to Hong Kong, so it is, as he puts it, "exploration time". Being mortal, and having arrived from Boston just a few hours earlier, he'd be entitled to some evidence of jet lag, a lack of clarity or courtesy, perhaps. But in the Horizon Club of the Island Shangri-La - his suggestion, and what better location to talk about evading the sorrows of old age? - he's the same reassuringly competent man conveyed by his writing. He takes statistical soundings ("How many articles do you write a week? A month?"), he's attentive to offered insights about the city (medical blunders/nursing home scandals), he fulfils the interviewee role. And he's on a deadline: he places his watch on the table where it ticks off the time left to us.

When was his most recent surgery? "Last week," he says, and obligingly holds out his capable hands. He specialises in endocrine procedures: thyroid, parathyroid, adrenal. "Surgery's not something I could ever let go. In two or three hours, I've done something that's made someone better. Writing for The New Yorker, on average you accomplish a project every six months. In public-health research or books, it's multi-year and totally uncertain. I need the dose of clear, focused gratification."

The previous week, he'd turned 50. Naturally, he was at work but his wife, Kathleen, conspired with his secretary to clear his schedule. Two of his best friends flew into town and they went to see a couple of films, one of which - Straight Outta Compton - is about rappers. In a different life, Gawande would like to have been a rock musician. (As a student, playing electric guitar, he and another guy called themselves Thousands of Breaded Shrimp.)

Now, he says, it's his children - Walker, Hattie and Hunter - who are "amazing musicians". Readers of Gawande know about his family. As he agrees, "All of them have had health issues I've written about. It's the problem of being in the family of a writer, they don't escape." When asked if he's been a patient himself, he says no, he's never been sick; then adds, scrupulously, "Well, I've had farsightedness and multiple cavities."

In fact, he had a medical problem as an infant that reshaped his parents' lives. His father, who came from a village 500km from what was then called Bombay, met his mother, who came from Ahmedabad, in New York, where they were both studying medicine. The plan was to return to India but a year or so after Atul was born, in 1965, he was vaccinated against smallpox, developed a rare complication and couldn't receive booster doses. It wasn't until December 1979, when the World Health Organisation (WHO) declared the global eradication of smallpox, that the Gawandes could plan their son's first visit to India.

By then, the family had settled in Ohio, in the poorest county in the state; his father "drove the only Mercedes in town". One of the reasons Gawande knew little about death, he writes, was because there were no grandparents in the New World. His is the classic immigrant's tale.

"In order to belong, you try to accomplish," he says, ruefully. "But accomplishment is never enough." (A little later, when I ask about his children's names, he explains, "My wife's a southern girl. The kids look like me but she got to give them southern names so she could lay claim to them. When the kids were small, people used to ask her in supermarkets if she nanny-ed for other people, too …")

At 26, Gawande was head of Bill Clinton's health care and social policy unit in Little Rock, Arkansas; this was when Clinton was running for president, in 1992, and considered an unelectable long shot. (As Gawande put it in one interview: "I suspect I was call No47 for the position".) Clinton won. But by then Gawande had discovered a love of surgery and, since he couldn't combine that with policy work, he turned to writing.

As it turns out, the writing is influencing policy. In 2009, he wrote a piece for The New Yorker called "The Cost Conundrum", about extreme health care costs in a town called McAllen, in Texas. "The primary cause," he deduced, "was, very simply, across-the-board overuse of medicine." A week later, a Democratic senator told The New York Times how Obama came into a large meeting of senators with the article and said, "This is what we've got to fix."

The Checklist Manifesto is a classic example of Gawande style: vivid (it begins with a three-year-old falling into an icy pond and being fished out, pulseless), comparative (standard aviation checklists helped save everyone on board the US Airways flight that landed on New York's Hudson River in 2009) and statistically optimistic (deaths in a Michigan intensive care unit that adopted the to-do checklist dropped by 66 per cent). He and his researchers worked with the WHO and eventually came up with the Safe Surgery Checklist. It consists of 19 questions as basic, but essential, as "Do we have the right patient?"

Surgery's not something I could ever let go. In two or three hours, I've done something that's made someone better.
Atul Gawande





In the same way, Being Mortal is about the quality-of-life checklist. And now Gawande is, again, his own guinea-pig because his widowed mother, 79 and living alone in the Ohio family house, is becoming vulnerable. She has "some memory issues". He's found himself following the thread he'd already laid down talking to his father, asking about her fears, worries, preferences.

"They've become the most meaningful conversations I've had, ever, with my mother," he says.

Towards the end of 2014, Gawande delivered the four BBC Reith Lectures. In the first one, he told the story of his 11-day-old son Walker's serious illness. In the final one, in December, he told the story of his father's death. I listened to it on the radio in Northern Ireland, where my own father, who'd had dementia for more than 12 years and had been in a home for a decade, was in hospital receiving antibiotics that prolonged an anguished existence. I'd spent those years commuting, for months at a time, between here (Hong Kong) and there, in a no-man's land where no communication - no conversation - was possible.

Being Mortal doesn't address the issue of dementia. Nonetheless, Gawande's voice was a comfort. (As The Daily Telegraph's radio critic Gillian Reynolds said of the lectures, which are still available on the BBC's website, he talks "clearly and gently, as if he's speaking to the listener as well as the audience in the hall".) Answers to the questions he raised - what's the most appropriate medical treatment? Is actually having medical treatment appropriate? - had already been pummelling my emotions; it was a relief to hear an informed outsider discuss them. I talked about Gawande's book and his lectures to my siblings. When our father became ill again, we agreed as a family: no more hospitals, no more antibiotics.

When I tell him this, and ask how to approach the particular curse of dementia, he sighs and says, "I still feel I'm chronicling my own learning process. What interests me in medicine is what it means to be good at what we do. But what does it mean to be good in those circumstances?" He suggests earlier conversations so that, later on, "you can know that you're being faithful" to the individual's wishes.

But it's not as simple as that; and he knows this, too. I'd read that he keeps a list on his phone of writing ideas and, when I ask to see it, he obliges. The topics are numbered. He's up to 350 and the most recent one is: dementia.

"I've been thinking about it," he says. "Thinking of a way in … it's because of a patient."

He's "nervous", he says, about assisted dying.

"My great worry is the slippery slope. In the Netherlands, 3 per cent of the population die by assisted death, and a subset of people do it because they feel they're a burden on others. The Netherlands was one of the latest countries to have advanced palliative and hospice care … Our goal is not a good death. Our goal is as good a life as possible until the end."

Of his own inevitable deterioration (having just stepped into the second half of his life), he says, "My feeling is that as long as my brain's working, I can tolerate being Stephen Hawking. But my wife always says, 'You know if I'm happy, you know if I'm sad. If I look happy, keep me going. If I look sad - don't.'"

The following day, at the Asia Society talk, he is asked about living wills ("Studies find they might not be helpful for families later") and Do Not Resuscitate orders ("DNR is an instruction at the end of communication - that isn't a discussion"). It is one of the biggest weekday lunches the Asia Society has ever held and the crowd is noticeably attentive.

There's a reason Hong Kong made it through the 2,500-plus list of speaking requests. Ronnie Chan Chichung, chairman of the Hang Lung Group, is also chairman of the Asia Society Hong Kong; in 2014, he and his brother, Gerald, donated US$350 million to Harvard's School of Public Health, and it is now officially the Harvard T.H. Chan School of Public Health. (The gift was the largest in Harvard's 379-year history.) Before the lunch, Chan made a speech in which he revealed that his brother and Gawande had recently been on the phone when Gerald's wife had suddenly fallen and, as it turned out, fractured her wrist. Gawande had, intercontinentally, advised that she seek medical help.

"You're a good doctor, Professor!" Chan enthused.

Indeed. But Gawande speaks humbly about his wife's 14-year-old cousin, Callie, who died of Hodgkin's lymphoma. When she was diagnosed, the family had turned to him. He writes about it in his 2007 book, Better. At the Asia Society, he says, "I regret to this day the conversations I had, I was totally unhelpful. They wanted to offer her some quality of life. I didn't help them articulate that."

He's trying to improve that situation for all of us. Earlier, I was professionally curious to know what the Chinese journalists had asked him in their interviews.

"They were like you," he said. "They talked about their parents."