Time affects almost all aspects of the practice of medicine. From how we think about diagnoses to treatments and even the tests we run to identify what's happening with the patient. Time also plays an important role in the practice and business of healthcare. First, let's look at clinical care, starting with diagnoses. Most clinical diagnoses can be separated into two categories based on time, acute and chronic. Acute conditions are those that are severe and sudden and onset, often, we think of acute conditions as something that happens and then resolves, like breaking a bone. Chronic conditions, on the other hand, are conditions that develop and worsen over time, like diabetes. Sometimes chronic conditions can produce acute conditions like an asthma patient can develop an exacerbation or worsening of their asthma that ultimately resolves. Moreover, the impact and meaning of these conditions may be different. For example, for a number of acute conditions, we don't really think of them as having a long-term impact or meaning on a patient's health. For example, you don't typically go on to develop diabetes because you broke your arm or got a cold in the eighth grade. Whereas chronic conditions may impact your overall health, including acute conditions like diabetes, making it harder to heal from infections. The timing of acute conditions may mean different things, for example, babies who have a lot of broken bones may indicate abuse or a serious disorder like osteogenesis imperfecta. Kids and young adults with a number of broken bones probably just have active hobbies or risky behavior, whereas older adults who are breaking multiple bones may indicate osteoporosis. Time also plays a role in treatment, many medications are only to be used for a short period of time like antibiotics. These drugs are prescribed and filled for a defined period of time, say days to weeks. Other medications may be treating chronic conditions and the patient is expected to be on them for years. Often, the longest any single prescription will be is for one year to allow the provider to re-evaluate if continued treatment is appropriate at regular intervals, even if the patient is expected to stay on the medication for the foreseeable future. These medications may be discontinued for a variety of reasons, including that the patient's condition no longer needs treatment, like a patient with hypertension, changing their diet and no longer actually needing blood pressure lowering medications. Other times, the patient may develop side effects to a medication that cause them to need to change therapies, like the development of a cough while on ACE inhibitors. Still other times, financial causes like a change in insurance affect which medications are covered and may cause a medication change. Finally, time is important even for laboratory tests, some tests actually capture different time windows of impact. For example, when trying to understand the levels of inflammation a patient may be experiencing, clinicians typically run two tests, C-reactive protein or CRP, and erythrocyte sedimentation rate or Sed rate. CRP measures acute inflammation and it's detectable within 24 hours, whereas the Sed rate will take longer to rise and be slower to resolve after an infection. Plus if we oversimplify it a bit, clinicians can use CRP to understand the amount of inflammation of patient has right now, while Sed rate tells them about longer-term inflammation. In other tests, the timing affects the accuracy of the test, for example, urine creatinine levels can vary based on food and liquid intake. So any individual measurement may not be accurate. Thus, providers may choose to order a 24-hour urine collection where all the urine produced over a full 24 hours are collected to get a more consistent and accurate measure of absolute creatinine levels. Whether it's through these tests, diagnosis or treatment, time definitely affects Madison. Now, let's think about how time affects the practice and business of health care. Time plays an important role in understanding the types of encounters provided by healthcare organizations. Visits that last longer than 24 hours are typically considered inpatient stays at a hospital. Though there are now longer observation periods that can be financially classified as an outpatient encounter, even though it looks very much like an inpatient stay. Financially, there's also a new concept of an episode of care. This terminology in the United States became common as health care payment reform developed what are called bundled payments. In this model, health care providers are paid a set amount for all care related to a single event. For example, if a patient has knee replacement surgery then all pre and post-op care is reimbursed with a single payment and it is the same for all patients. If one patient goes on to develop a complication and needs additional medical care, no additional payments will be made by the insurance provider and the healthcare provider may lose money. Understanding how to group events that count as part of an episode of care is complex and based both around the timing and the reason of care following a procedure.