Characteristics of the rehabilitation medicine population

Rehabilitation medicine is practiced in a variety of settings such as acute medical and surgical wards, inpatient rehabilitation facilities, nursing homes, outpatient clinics, and even the patient’s home. Physiatrists are an integral part of the care provided in many of these settings and are often consulted to provide diagnostic and therapeutic services and expertise to individuals with a variety of diagnoses such as spinal cord injury (SCI), traumatic brain injury, stroke, and musculoskeletal pain syndromes. In this role, it is imperative that physiatrists have a working knowledge of various medications as well as the principles of medication safety. This article provides the reader with a foundation in the general and specific aspects of medication safety as they apply to the practice of rehabilitation medicine.

Adverse drug events

Adverse drug events (ADEs) are a consequence of pharmacotherapy in patient care. The average rate of ADEs in a hospital setting range from 2 to 7 events per 100 admissions, giving an annual occurrence of 770,000. The estimated average direct cost to a hospital is $5.6 million dollars per year. The true cost, which includes hospital readmission, lost productivity, and legal proceedings and settlements, is much greater and difficult to assess.

The definition of an ADE is any injury from the use of a drug. This avoids the labeling of a reaction as an ADE. A distinction should be made between ADEs and adverse drug reactions (ADR), which are events or injuries occurring in normal prescribing practices (ie, normal doses and frequencies). ADR include side effects that are known reactions to medication and are listed in the detailed prescribing information as well as allergic reactions, which are unexpected and unpredictable immune responses. Other than ADRs, ADEs are also secondary to medication errors, as discussed later. ADEs secondary to medication errors are more common but may or may not result in patient harm. These types of ADEs should be listed as preventable ADEs.

Reporting ADEs is the single most important aspect to identifying and assessing process failures within a health care system. When reporting an ADE, it is important to supply as much information regarding the patient and situation as is needed to allow an understanding of not only what happened but why the event occurred. An ADE should also be listed in the patients’ medical record and appropriate updates to allergy and medication intolerance profiles should be made to prevent the same reaction from recurring, if applicable. Reporters should understand that the process is nonpunitive and is meant to identify process failures. ADEs can be classified by severity: mild, moderate, and severe, with descriptions noted in Table 1 .

Administrative bodies such as a medication safety committee or a pharmacy and therapeutics committee are hospital-specific organizations that evaluate ADEs on a regular basis. The multidisciplinary committees meet either monthly or quarterly and, based on observed trends, can initiate further inquiries into medication use at the facility. Actions taken by these committees can include initiation of a medication-specific protocol, drug restriction, and/or removal from the institution’s formulary. On a wider level, MedWatch is a reporting system set up by the US Food and Drug Administration (FDA) to track approved medications. Voluntary submissions are assessed to determine whether regulatory actions are required, which can include mandatory warnings, labeling changes, requests for postmarketing studies, or withdrawal of a medication from the market.

Adverse drug events

Adverse drug events (ADEs) are a consequence of pharmacotherapy in patient care. The average rate of ADEs in a hospital setting range from 2 to 7 events per 100 admissions, giving an annual occurrence of 770,000. The estimated average direct cost to a hospital is $5.6 million dollars per year. The true cost, which includes hospital readmission, lost productivity, and legal proceedings and settlements, is much greater and difficult to assess.

The definition of an ADE is any injury from the use of a drug. This avoids the labeling of a reaction as an ADE. A distinction should be made between ADEs and adverse drug reactions (ADR), which are events or injuries occurring in normal prescribing practices (ie, normal doses and frequencies). ADR include side effects that are known reactions to medication and are listed in the detailed prescribing information as well as allergic reactions, which are unexpected and unpredictable immune responses. Other than ADRs, ADEs are also secondary to medication errors, as discussed later. ADEs secondary to medication errors are more common but may or may not result in patient harm. These types of ADEs should be listed as preventable ADEs.

Reporting ADEs is the single most important aspect to identifying and assessing process failures within a health care system. When reporting an ADE, it is important to supply as much information regarding the patient and situation as is needed to allow an understanding of not only what happened but why the event occurred. An ADE should also be listed in the patients’ medical record and appropriate updates to allergy and medication intolerance profiles should be made to prevent the same reaction from recurring, if applicable. Reporters should understand that the process is nonpunitive and is meant to identify process failures. ADEs can be classified by severity: mild, moderate, and severe, with descriptions noted in Table 1 .

Administrative bodies such as a medication safety committee or a pharmacy and therapeutics committee are hospital-specific organizations that evaluate ADEs on a regular basis. The multidisciplinary committees meet either monthly or quarterly and, based on observed trends, can initiate further inquiries into medication use at the facility. Actions taken by these committees can include initiation of a medication-specific protocol, drug restriction, and/or removal from the institution’s formulary. On a wider level, MedWatch is a reporting system set up by the US Food and Drug Administration (FDA) to track approved medications. Voluntary submissions are assessed to determine whether regulatory actions are required, which can include mandatory warnings, labeling changes, requests for postmarketing studies, or withdrawal of a medication from the market.

Medication errors

As mentioned earlier, medical errors, and in particular medication errors, are rigorously scrutinized, reported, and investigated in the health care industry, and by state and federal governments. The FDA ( www.fda.gov/medwatch.htm ), Institute for Safe Medication Practices ( www.ismp.org ), US Pharmacopeia ( www.usp.org ), and MedMARX ( www.medmarx.com ) are some of the bodies that track medication errors in the United States. Medication errors represent the largest single cause of errors in the hospital setting, accounting for more than 7000 deaths annually.

Common types of errors are caused by (1) inadequate knowledge about the drug, (2) insufficient knowledge about the patient, (3) rules violations, (4) slips and memory lapses, (5) transcription errors, (6) faulty drug identity checking, (7) faulty communication with other services, (8) inadequate monitoring, and (9) drug stocking and delivery.

Leape and colleagues reported more than 15 types of medication errors: wrong dose, wrong choice, wrong drug, known allergy, missed dose, wrong time, wrong frequency, wrong technique, drug-drug interaction, wrong route, extra dose, failure to act on test, equipment failure, inadequate monitoring, preparation error, and others. Of the 130 errors for physicians, most involved the wrong dose, wrong choice of drug, and known allergy. Among the 126 nursing administration errors, most were associated with wrong dose, wrong technique, and wrong drug. Each type of error occurred at various stages, although some occurred more often during the ordering and administration stages.

Medication reconciliation

Medication reconciliation is an important practice at all points along the health care continuum of care. Given that more than half of all hospital admissions have at least 1 medication discrepancy, with 33% having mild to moderate harm potential, and 6% severe harm potential, there is significant room for improvement. Common errors include incorrect doses/frequencies, missing medications, and inappropriate durations of use.

Medication reconciliation is described as the process of avoiding inadvertent inconsistencies across transitions in care by reviewing the patient’s complete medication regimen at the time of admission, transfer, and discharge, and comparing it with the regimen being considered for the new setting of care. How that process is determined is up to the specific institutions and vary in several features but there are some basic recommendations for what the process should entail. The Institute for Healthcare Improvement (IHI) suggests at least 3 steps to the process: verify by collecting the list of medications, vitamins, nutritional supplements, over-the-counter drugs, and vaccines; verify that the medications and dosages are appropriate; reconcile and document any changes.

Other aspects to this process include (1) specifying responsibilities for each health care discipline; (2) using a standardized form for regimen evaluation; (3) determining an explicit time frame for completion that is relevant to the setting (eg, ambulatory vs acute care); (4) implementation of educational programs for health care professionals as well as patients and caregivers, and designing a monitoring process to ensure compliance and evaluate for improvement.

Strategies for improving medication reconciliation compliance vary from basic health care provider education to implementation of advanced information technology. However, it is not yet agreed as to what is an effective implementation. Studies investigating the impact of a pharmacist-led intervention or the implementation of electronic medical records show improvement in the reduction of preventable ADEs but the results are mixed and inconsistent.

Currently, The Joint Commission (TJC) has suspended the enforcement of the National Patient Safety Goal (NPSG) #8, which requires health care systems to accurately and completely reconcile patients’ medications across the continuum of care. As medication reconciliation becomes more standardized and monitoring processes are better refined, this aspect of patient care will be enforced with as much emphasis as the other NPSGs.

Patient and family education

Poor compliance with a medication regimen is a long-standing problem, leading to unnecessary disease progression or complications, decline in the functional abilities, increased numbers of visits to the emergency room, increased hospital readmission rates, reduced quality of life, and even death.

According to the World Health Organization (WHO), only about 50% of patients who suffer from chronic diseases take their medicines as prescribed. In the United States, nonadherence affects Americans of all ages, both genders, and involves higher-income, well-educated people just as much as those at lower socioeconomic levels. Between 12% and 20% of patients take other people’s medicines ; following a heart attack, only 45% of patients regularly take β-blocker (BB) medications during the first year after leaving the hospital ; less than 2% of adults with diabetes follow the American Diabetes Association recommendations.

In its report “To Err is Human; Building a Safer Health System,” the Institute of Medicine (IOM) encouraged clinicians to educate their patients about (1) the medications they are taking, (2) reasons why they are taking them, (3) what the medications look like, (4) time of day that the medications should be taken, (5) potential side effects, (6) what to do if they experience side effects, and (7) need for regular testing.

Strategies for improving patient adherence include increasing patient and family awareness about medications through discussions at the time that the health professional (1) writes the prescription and (2) at the time that the patient fills the prescription at the pharmacy. These discussions are best accomplished by relaying the most important information first, repeating key points, having the patient restate key instructions, and encouraging the patient to ask questions and share information. Most individuals want from their physicians all information concerning possible adverse effects of the prescribed medication and do not favor physician discretion in these decisions.

Patients forget more than half of the information obtained from a verbal explanation immediately after hearing it. Because many patients commonly seen by physiatrists suffer from diseases manifested by cognitive impairment, such as stroke or brain injury, a partner or caregiver who accompanies the patient to doctor visits should be welcomed and encouraged to take notes during the discussion, and written information about the treatment should be provided to them.

Other ways to improve adherence include (1) tailoring the medication regimen to the patient’s daily schedule, (2) decreasing the number of doses to once or twice daily, (3) eliminating unnecessary medications or using combination products, (4) changing the route of administration, and (5) decreasing the overall cost of the medication regimen if necessary. In a study published in JAMA comparing compliance rates for daily dosing versus twice a day, 3 times a day, and 4 times a day, compliance rates averaged 76% during 3428 days observed; 87% of the once daily, 81% of the twice daily, 77% of the 3 times a day, and 39% of the 4 times a day dosages were taken as prescribed.

Medication safety in patients with dysphagia

Dysphagia is a clinical syndrome defined as an inability to swallow, or a sensation that solids or liquids do not pass easily from the mouth to the stomach. This condition can occur in patients with structural deficits or dysfunction of the oral cavity and/or pharynx secondary to neurologic or muscular disorders. Some common and potentially life-threatening consequences of dysphagia include choking, aspiration, pneumonia, malnutrition, and dehydration. These consequences are of increased importance in the rehabilitation unit, where the patients commonly present with impaired mobility and tend to remain in a supine position for prolonged periods of time.

Certain medications can cause or even exacerbate an existing dysphagia. Sedatives may affect swallowing by acting on the central nervous system. Anticholinergics or diuretics can make chewing and swallowing difficult because of decreased saliva production. Other medications, such as nonsteroidal antiinflammatory drugs (NSAIDs), bisphosphonates, potassium chloride, quinidine, tetracyclines, clindamycin, and iron products, can result in esophageal injury when not taken properly or when esophageal motility is impaired.

Patients after endotracheal intubation or tracheostomy may have different degrees of dysphagia caused by soft tissue injuries at the oropharyngeal level. Older patients are also at higher risk for dysphagia caused by decreased oropharyngeal motility and reduced saliva production. The type of diet (eg, pureed, chopped, regular), fluid thickness, and other techniques to improve the patient’s dysphagia need to be implemented on an individual basis. Changes may be necessary in the medication regimen or in the way medications are administered because some may be difficult to swallow or are potentially dangerous if crushed or chewed, whereas others should not be crushed (enteric coated, extended release, long acting, controlled release, and sustained release). Liquid and capsules are the preferred form of medication for patients with dysphagia.

The role of the clinical pharmacists in medication management

Clinical pharmacists are experts in the therapeutic use of medications and have the ability to provide recommendations on the safe, appropriate, and cost-effective use of medications. They are involved in direct care patient rounds, medication order review, patient counseling, medication therapy management, participation in procedures that use high-risk medications, medication procurement, providing drug information services, and documentation of interventions. Clinical pharmacists play an integral role in preventing medication errors as part of the health care multidisciplinary team.

Medication-Induced Falls

Medication-induced falls in the geriatric or rehabilitation population are a significant concern. The most recent American Geriatrics Society (AGS) and British Geriatrics Society (BGS) clinical practice guidelines on the prevention of falls in older persons note 3 specific medication-based recommendations :

• •
  

  Minimization or withdrawal of psychoactive medications when possible

  
  
• •
  

  Reduction in total number of medications or dose in individual medications

  
  
• •
  

  Review all medications for possible minimization or withdrawal.

The main focus of these recommendations is on the unnecessary use of medication or overprescribing practices that can be noted as polypharmacy. Studies have shown that the number of drugs a patient is on is a significant predictor of falls, with the greatest risk occurring in patients with regimens of 4 or more medications.

Medications that have been identified that increase risk for falls are listed in Table 2 . Multiple meta-analyses have been published evaluating the specifics of drug classes and their fall-risk potential. These analyses identified neuroleptics/antipsychotics, antidepressants, benzodiazepines, and sedatives/hypnotics as high risk for falls. Narcotic agents were not associated with an increased risk of falls and antihypertensives, with the exception of diuretics, were not consistently associated with an increased risk.

The mechanisms behind drug-induced falls are multifactorial and range from alterations in hemodynamics (specifically orthostatic hypotension) to sedation via multiple mechanisms and receptor activities. Antihypertensives work in multiple fashions but all medications of this class can cause falls via syncope secondary to orthostatic hypotension. Orthostatic hypotension, or postural hypotension, is defined as a reduction in the following within 3 minutes of changing position from sitting to standing or laying down to sitting :

• •
  

  Systolic blood pressure of at least 20 mm Hg; or

  
  
• •
  

  Diastolic blood pressure of at least 10 mm Hg.

Chronic antihypertensive therapy has not been associated with an increased risk for fall but rapid titration of drugs in this class can predispose a patient to falls. A recommendation for preventing this occurrence is to allow an adequate time between dose increases to allow the medication to reach its maximal effect.

Sedation by centrally acting medications is the major concern for the higher-risk medications, particularly the antipsychotics that act on multiple receptors. This reduction in wakefulness increases the risk for fall by impairing balance and reducing response time. It can occur via multiple mechanisms via receptor activity, predominantly antagonism of histamine, α-1, and muscarinic receptors or agonism of γ-aminobutyric acid (GABA) and opioid receptors.

Interventions to reduce medication-induced falls continue to be difficult to apply to clinical practice because of a lack of details of the medications taken in the study population as well as variability of practice settings. One clinical trial by Campbell and colleagues noted a 66% reduction in the risk of falling (hazard ratio 0.34, 95% confidence interval 0.16–0.74) after a gradual withdrawal of psychotropic medications. However, 47% of these patients required restarting the medication after only 1 month. Pharmacist-led medication review as an intervention was studied as a fall-preventative measure and showed a significant improvement compared with the control group in the number of falls per patient (0.8 vs 1.3 falls per patient, P <.0001). Another retrospective study evaluating the collaboration of a consultant pharmacist, research nurse, and a physician in a rehabilitation unit showed reductions in cardiovascular (CV) drugs, analgesics, psychotropics, and sedatives that correlated with a 47% reduction in falls in the intervention group.

These studies emphasize the need for regular medication profile monitoring performed by a pharmacist or any other health care practitioner. Other general prescribing practices that may aid in reducing or limiting the potential for falls is to use the lowest effective dose, avoid unneeded polypharmacy, evenly divide fall-risk medications that require multiple doses per day (ie, use dosing every 12 hours instead of twice a day), avoid the use of multiple sedating medications on an as-needed basis, and shift to bedtime dosing of sedating medication if possible.

Geriatric pharmacokinetics and pharmacodynamics

Pharmacokinetics and pharmacodynamics are more unpredictable in the elderly than in the younger population because of natural body changes that are caused by aging. In addition, there are limited data regarding the use of medications in the elderly because of extensive exclusion criteria in research studies.

Pharmacokinetics refers to the processes of absorption, distribution, metabolism, and excretion. As people age, certain physiologic changes occur: decrease in total body water and muscle mass, but an increase in body fat. Organ function starts to decrease by the third decade, and by the sixth decade the reduction reaches 25%. Medication regimens need to be tailored accordingly.

Drug interactions

Clinicians should be aware of potential drug interactions because they are common (about 7%–25%), underreported, result in dissatisfaction with care, and frequent emergency department visits. Predisposing risk factors include polypharmacy, multiple comorbidities, use of drugs with narrow therapeutic ranges, and increased age. The goal of medication metabolism is to make the drug more polar and readily available for excretion. Most of the drugs are metabolized through the liver. Phase I metabolism (oxidation, reduction, and hydrolysis) is predominantly catalyzed by the cytochrome P450 superfamily of mixed oxidases (CYP), which is organized into 18 families (ie, CYP3) and 43 subfamilies (ie, CYP3A4). Primary CYP 450 enzymes include 3A4, 2D6, 2C9, 2C19, 1A2, and 2E1. More than 50% of all hepatic reactions occur through CYP3A4. Drug interactions occur through various mechanisms such as induction/inhibition of metabolism of the medications, reduced absorption, altered gastric pH, and inhibition of renal tubular transport. Dose adjustments are advisable to avoid subtherapeutic or supratherapeutic effects of interacting medications.

Warfarin is one of the most common medications seen in rehabilitation practice because of its wide indications. It is metabolized to S and R enantiomers. S enantiomer is 3 to 5 times more potent than R enantiomer, thus drug interactions with S enantiomer are more significant. S enantiomer is metabolized through CYP 2C9, whereas R enantiomer is primarily metabolized by CYP 1A2 and CYP 3A4. Significant drug interactions of warfarin are shown in Table 3 . Bleeding risks increase with addition of aspirin at more than 1.5 g/d, NSAIDs, penicillins at high doses, tamoxifen, rivaroxaban, and natural supplements (Ginkgo biloba or St. John’s wort). The combinations mentioned earlier should be avoided.

Anticoagulant pharmacology

Venous Thromboembolism

Venous thromboembolism (VTE) is a serious but preventable cause of morbidity and mortality in hospitalized patients in rehabilitation that can be reduced by means of mechanical or pharmacologic thromboprophylaxis. Treatment options include early ambulation, use of stockings and alternating pressure devices, and antithrombotic agents ( Tables 4–6 ). Although early mobilization is recommended for mildly affected patients, seriously ill patients or those with severe motor impairments often cannot return to walking. For patients who are at high risk of bleeding and patients with intracranial or active GI bleeding, compression stockings and intermittent compression devices are reasonably effective options. Pharmacologic agents should be initiated as soon as it is medically safe. The anticoagulation type, intensity, and duration should be adjusted on an individual basis depending on bleeding risk.

Table 4

Anticoagulants for deep vein thrombosis (DVT) prophylaxis and their properties

	Mechanism of Action	Route	Pharmacokinetics	Common Adverse Events	Common Drug Interactions	Monitoring	Reversal
Dabigatran a	Direct thrombin inhibitor (factor IIa)	By mouth	Elimination: renal (80%) Half-life (normal renal function): 12–17 h	Hemorrhage, dyspepsia (abdominal/epigastric discomfort/pain), nausea, vomiting, constipation, abnormal liver enzymes	Substrate of P-glycoprotein: ketoconazole, verapamil, amiodarone, quinidine, clarithromycin, rifampin, PPIs, atorvastatin	No monitoring required; prolongs ecarin clotting time, aPTT, PT/INR, thrombin time	No antidote available
Dalteparin	Inhibition of factor Xa and IIa	Subcutaneous	Elimination: renal Half-life (normal renal function): 2–5 h Duration of effect: 12 h	Hemorrhage, thrombocytopenia (including HIT), abnormal liver enzymes, local injection site hematoma	Concomitant anticoagulants	No routine monitoring required; anti-Xa levels may be monitored in obese patients (>190 kg); other coagulation tests not affected	Protamine sulfate (1% solution), at a dose of 1 mg protamine for every 100 units of dalteparin given
Enoxaparin	Inhibition of factor Xa and IIa	Subcutaneous, IV	Elimination: renal (40%) Half-life (normal renal function): 7 h Duration of effect: ∼12 h	Hemorrhage, thrombocytopenia (including HIT), nauseam diarrhea, abnormal liver enzymes, local injection site hematoma	Concomitant anticoagulants	No routine monitoring required; anti-Xa levels may be monitored in obese patients (>190 kg); other coagulation tests not affected	Protaminesulfate (1% solution) at a dose of 1 mg of protamine for every 1 mg of enoxaparin if administered <8 h; if >8 h 0.5 mg of protamine per 1 mg of enoxaparin
Fondaparinux	Inhibition of factor Xa	Subcutaneous	Elimination: renal (77%) Half-life (normal renal function): 17–21 h	Hemorrhage, fever, nausea, anemia, abnormal liver enzymes, local injection site hematoma	Concomitant anticoagulants	No routine monitoring required; other anticoagulation tests not affected	No antidote available; intermittent dialysis
Heparin	Inhibition of factor Xa and IIa by binding to antithrombin	Subcutaneous, IV	Elimination: renal Half-life (normal renal function): 1–2 h	Hemorrhage, local injection site hematoma, hyperkalemia, hypersensitive reaction, HIT abnormal liver enzymes, osteoporosis (long-term administration)	Concomitant anticoagulants	Routine monitoring of aPTT or anti-Xa when used as treatment	Protamine sulfate (1% solution), at a dose of 1 mg per 100 units of UFH if administered <1 h, 0.5 mg of protamine per 100 units of UFH if administered within 1–2 h, 0.25 mg of protamine per 100 units of UFH if administered >2 h ago
Rivaroxaban	Inhibition of factor Xa	By mouth	Elimination: renal (66%), hepatic (28%) Half-life (normal renal function): 5–9 h	Hemorrhage, abnormal liver enzymes, thrombocytopenia	Substrate for CYP 3A4 and P-gp: fluconazole, ketoconazole, itraconazole, ritonavir, conivaptan, macrolide antibiotics, diltiazem, verapamil, quinidine, amiodarone, carbamazepine, phenytoin, rifampin, St. John’s wort, clopidogrel	No routine monitoring required. aPTT and PT may be increased in some	No antidote available, not dialyzable
Warfarin	Vitamin K antagonist, inhibition of factors II, VII, IX, and X	By mouth	Elimination: renal (92%) Half-life: 20–60 h	Hemorrhage, skin necrosis (early onset, <7 d), purple toe syndrome (late onset, 7–10 wk), abnormal liver enzymes	Substrate for CYP 2C9, 3A4, and 1A2. Amiodarone, trimethoprim/sulfamethoxazole, metronidazole, azole antifungals, clarithromycin, erythromycin, diltiazem, ritonavir, ciprofloxacin, levofloxacin, cimetidine, carbamazepine, phenytoin, rifampin, St. John’s wort, grapefruit juice	INR	Vitamin K depending on INR; by mouth formulation preferred See Table 5 for specific management of supratherapeutic INR

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