Oct 22 (Reuters) - HCA Healthcare Inc reported better-than-expected quarterly earnings on Friday and raised forecasts for the year as the U.S. hospital operator treated a surge of sicker patients requiring costlier care due to the Delta variant.

Patient volumes rebounded across most segments, with outpatient surgeries and emergency room visits rising 6.4% and 31.2%, respectively, on a same-facility basis.

Chief Executive Officer Sam Hazen said the company experienced "the most intense surge yet of the pandemic" during the quarter.

But shares of the company were choppy in pre-market trading as market participants also weighed the upbeat outlook against higher costs, with expenses incurred on staff salaries and benefits rising 16.4% or nearly a billion dollars to $7.09 billion in the quarter.

A nationwide shortage of healthcare workers is forcing hospitals to pay more to recruit nurses and technicians.

But the higher patient numbers prompted the hospital operator to raise its earnings forecast to a range of $17.20 to $17.80 per diluted share this year, from a prior forecast of $16.30-$17.10 per share.

Same-facility equivalent admissions, a measure of patients staying overnight at a hospital and those treated on an outpatient basis, rose 9.3% in the quarter.

Revenue for the quarter was $15.28 billion, beating analyst estimates of $14.48 billion.

(Reporting by Mrinalika Roy and Leroy Leo in Bengaluru; Editing by Arpan Varghese)