SEPTEMBER 13, 2015

TERRE HAUTE, Ind. — The nation’s health care providers are under orders to start using a new system of medical codes to describe illnesses and injuries in more detail than ever before. The codes will cover common ailments: Did a diabetic also have kidney disease? But also included are some that are far less common: whether the patient was crushed by a crocodile or sucked into a jet engine.

The more than 100,000 new codes, which will take effect on Oct. 1, have potential benefits, as they will require doctors to make a deeper assessment of many patients.

But the change is causing waves of anxiety among health care providers, who fear that claims will be denied and payments delayed if they do not use the new codes, or do not use them properly. Some doctors and hospitals are already obtaining lines of credit because they fear that the transition to the new system will cause cash-flow problems.

“It’s a sea change for physicians,” said Dr. Pardeep Kumar, a 46-year-old internist here who is counting down to Oct. 1. “We will have to be very much more specific.”

Under the new coding regime, government programs and private insurers will require doctors, hospitals, clinics and nursing homes to report vastly more information about the care they provide. Dr. Kumar, who is in practice with his wife, and physicians across America will try to answer questions like these:

Did a diabetic also have kidney disease, eye problems or nerve damage? Did a patient with high blood pressure also have signs of congestive heart failure? Was that broken finger on the left or right hand? Was the fracture in the top, bottom or middle of the finger?

Was the patient bitten by a horse, a snake or a shark? Pecked by a turkey? Crushed by a crocodile? (Code W58.13.) Or sucked into a jet engine? (Code V97.33.)

The new catalog of codes includes more than 100 for gout and more than 200 for diabetes. In a sign of the times, the government lists more than 30 codes for injuries caused by acts of terrorism.

The codes, from the 10th revision of the International Classification of Diseases, or ICD-10, have significant implications for patients. For example, Dr. Kumar said, doctors may need to perform additional tests to help determine if a patient with high blood pressure has heart failure.

ICD-10 includes 68,000 diagnostic codes, compared with 14,000 in the current compendium. The number of codes for inpatient hospital procedures will expand to 87,000, from 4,000.

Consumers often need prior approval from insurers for expensive tests and medical procedures. To get approval, they need a valid diagnostic code.

Dr. Michael R. Marks, an orthopedic surgeon and coding expert in Connecticut, said that if doctors did not use the proper codes, insurers could delay approval. “The patient,” he said, “will get frustrated and ask: ‘Why has my M.R.I. not been authorized yet? Why has my surgery not been scheduled?’ ”

Professional coders play an invisible but indispensable role in the health care system, reading through medical records and assigning codes to describe patients’ conditions. Accurate coding helps ensure patients get the care they require. It is also a way to justify the services provided. The old codes, in use for more than 30 years, have not kept up with changes in medical technology and treatment.

Health care providers are racing to hire coders as the deadline approaches.

Coders are “a hot commodity,” said Kevin M. Carpenter, director of health information management at Rush University Medical Center in Chicago, who estimated that his hospital had spent $5 million preparing for the new codes. That includes the cost of upgrading information technology and training 1,000 doctors and 30 full-time coders.

The imminent shift dwarfs comparable changes. In 1983, Medicare started paying hospitals a fixed amount for each case, based on the diagnosis, but that was only for hospitals and Medicare patients. In 2014, under the Affordable Care Act, millions of people obtained Medicaid or subsidies for private insurance, but together those changes affected fewer than one in 10 Americans.

By contrast, the federal government says the new codes will be used by doctors and hospitals for virtually all patients.

As people make the change, doctors and hospital executives say, it is inevitable that some claims will be denied for services that were provided but not properly coded. Patients may see the denials in statements they receive from insurers.

Many doctors and hospitals say they will step up efforts to collect the patient’s share of the bill, including deductibles and co-payments, at the time of service.

Doctors and hospitals can revise and resubmit claims to correct the codes. But that takes time and could delay reimbursement.

“We fully expect delays in payment from some insurers,” said Brenda L. Reetz, chief executive of Greene County General Hospital in Linton, Ind. “We don’t have the cash flow of larger hospitals. So we got a $3 million line of credit from a bank, based on the money we expect to receive from Medicaid, Medicare, commercial insurers and patients.”

The hospital has been training employees since November 2013, but Cathy Hadley, director of health information management at the county-owned hospital, said, “It will take us 35 percent longer to do coding.”

On its website, Aetna says, “Medical claims will be denied if they don’t use the new ICD-10 codes” for services provided on or after Oct. 1. Stacie Watson, an Aetna executive, said: “We are ready. Test results are encouraging. There should be very little disruption if providers and everyone else is ready.”

But Dr. Barbara L. McAneny, a cancer specialist in Albuquerque, expressed concerns. “I don’t think physicians are ready,” she said. “I don’t think health plans are ready.”

Dr. McAneny, a trustee of the American Medical Association, said she and her 17-doctor group had taken out a $4 million line of credit to ensure they could pay expenses, including the cost of cancer drugs, if the new codes cause a delay in reimbursement.

Use of the new codes, originally scheduled for October 2013, was delayed a year by the Obama administration and then pushed back another year by Congress.

A Nashville bank, InsBank, is offering a special “ICD-10 Line of Credit” to doctors in Tennessee. “Cash may come in slower than usual,” said Blake J. Wilson, a vice president of the bank, but doctors must still pay rent, electricity bills and wages.

Insurers, researchers and some doctors see many potential benefits in use of the new codes. Doctors will have to provide more information about the cause, severity and complications of an illness or injury.

“That will require deeper assessment of the patient,” Dr. Kumar said.

The new codes will also make it easier for insurers and federal officials to measure the results of treatment and the quality of care — factors increasingly used in deciding how much to pay doctors and hospitals.

Public health officials say the new codes will help them identify outbreaks of disease, causes of death and community health needs. Researchers say the data will help them evaluate new treatments and procedures.

Dr. Robert W. Lash, a diabetes specialist who is chief of staff at the University of Michigan Health System, said: “ICD-10 is a lot more work for many providers, with no obvious short-term payoff. But in the long run, we should gain a better understanding of illnesses and injuries and how to treat them.”

Karen Zupko, a coding consultant in Chicago, said orthopedics would be affected more than other specialties because the codes for fractures and injuries are particularly complex. One code in the old system may be replaced by dozens of new options.

Dr. Marks, a former president of the Connecticut Orthopaedic Society, gave an example: A doctor will be asked to specify whether a fractured thigh bone is in the right or left leg; whether the bone protrudes through the skin; whether healing is routine or delayed; and whether the bone fragments rejoin at the wrong angle, leaving the patient with a deformed limb.

“The number of codes is exploding,” Dr. Marks said. “On Oct. 1, we will be speaking a new language. It’s like switching to German, after speaking English for 30 years.”

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