MILAN, April 11 (Reuters) - Exor, the investment arm of the Agnelli family, has a growing interest in the healthcare industry, where it has already invested almost 4 billion euros ($4.3 billion), CEO John Elkann said on Thursday.

"The increased cost of healthcare services combined with a shortage of medical staff is driving demand for innovative new approaches to tackle global health problems," he said in his annual letter to Exor shareholders.

Exor views healthcare as a "long-term, structural growth sector," said Elkann, the scion of the Agnelli family and chair of automakers Stellantis and Ferrari.

Exor's investments cover a broad range of industries, including manufacturing, media, fashion, sport and technology. In addition to Ferrari, it controls companies including agriculture and construction machine maker CNH and Serie A soccer club Juventus. It is also the single largest shareholder in Stellantis.

Exor entered the healthcare business in recent years both through direct investments in companies and through its venture capital arm, fuelled by the proceeds of the sale of its reinsurer PartnerRe in 2022.

Last year Netherlands-based Exor spent 2.6 billion euros to become the single largest investor in Philips with a 15% shareholding and in 2022 bought stakes in Frence's Institut Merieux and in Lifenet Healthcare, an Italian company managing hospitals and outpatient clinics.

It has said its main investment areas besides healthcare are technology and fashion.

Separately on Thursday, Exor announced that starting from Jan. 1, based on IFRS 10 European accounting rules, it changed its status from a holding company to an 'investment entity'.

This would allow it to deconsolidate portfolio companies from its balance sheet and simply account for them at their fair value, with an estimated one-off non-cash gain of approximately 12 billion euros.

Exor's net asset value (NAV) rose to 35.5 billion euros in 2023, up from 28.2 billion euros in the previous year, it said, mostly driven by the performance of Ferrari and Stellantis.

($1 = 0.9315 euros) (Reporting by Giulio Piovaccari;Editing by Elaine Hardcastle)