Dear Mr. Land,
Your best luck will be to look at each of the soldier's Compiled Service Record. This individual record has information (when mentioned) from names that were compiled from company muster rolls, clothing records, casualty list, POW records, hospital records, etc. A card was made on each soldier's name when it was mentioned in any of these type records and placed in a envelope for that soldier. The originals are at the National Archives in Washington, D.C. All Confederate CSRs have been microfilmed and copies are distributed through the states. You can obtain a copy of the Tennessee soldier's CSR through the National Archives ($37.00 per record), from the Tennessee State Library and Archives, the Chattanooga Public Library (3rd Floor), the Eastern Tennessee Historical Library and Archives (McClung Library) in Knoxville, Tennessee. The CSR's often did list the cause of death when it was known from the prison camp hospital records.
The "Official Records of the War of the Rebellion" did not list out causes of death for individual prisoners of war. It dealt with battle reports, letters, telegraphs, and other correspondence. It does have some prisoner of war related information, but it is in regards to the cartels and the handling of prisoners, supplying, etc. Broadfoot's "Supplemental" to the records add little else. Both multi-set volumes are only the tip of the iceberg when it comes to War Between the States records, and other documents that still exist. Much still remains in private hands, uncataloged in archives (county, state, Federal, private, and universities).
I hope this helps.
Gerald D. Hodge, Jr.
War Between the States Historian
Historian: 39th Georgia Volunteer Infantry Regiment