WEDNESDAY, Nov. 3 (HealthDay News) -- Psychiatric disorders are common among people who intentionally swallow foreign objects, a behavior that is costly for the health-care system, a new study shows.

Researchers at Rhode Island Hospital identified 305 cases of intentional ingestion of foreign objects at the hospital over eight years. The most common items were pens (24 percent), batteries (9 percent), knives (7 percent) and razor blades (7 percent).

The 305 cases involved 33 patients. Of those patients, 79 percent were previously diagnosed with a psychiatric disorder. More than half of the patients were diagnosed with a mood disorder, while others had anxiety, substance abuse, psychotic or impulse control disorders.

One patient was responsible for 67 of the cases while four patients accounted for 179 cases. About 53 percent of the patients were admitted from residential institutions, mostly from a state-run chronic psychiatric inpatient facility. Others came from private homes in the community (38 percent) or from prison (9 percent).

In the majority of the cases, the foreign objects were successfully retrieved during the initial endoscopic extraction attempt, most often from the stomach or esophagus. Only two cases eventually required surgery. There were no patient deaths.

Hospital costs for the 305 cases totaled $2,018,073 and most of that was paid for by Medicare or Medicaid. Most of the costs were due to nursing care (56 percent), followed by endoscopy, emergency department and surgical services.

"Foreign body ingestion is poorly understood, difficult to treat, and consumes considerable physician time and hospital resources. Attention should be focused on investigating how to avoid these preventable and costly episodes," the researchers concluded.

The study appears in the November issue of Clinical Gastroenterology and Hepatology.

More information

For more on obsessive-compulsive disorder, go to the National Institute of Mental Health.