A drop in patient bill collections late last year dealt a severe blow to Quorum Health’s liquidity and led to its bankruptcy filing Tuesday, executives said in a regulatory filing.

Until recently, Brentwood-based Quorum contracted with Community Health Systems — the company from which it was spun out four years ago — for revenue cycle and other services. The companies’ relationship soured over those deals, however, and Quorum President and CEO Bob Fish and his team last spring said they planned to switch to R1 RCM for bill collections. The move, they told investors, would quickly generate $10 million in much-needed savings for Quorum.