Serious interactions of prescription medications with over-thecounter (OTC) agents and alcohol are common among older adults (Manasse, 1995; The Task Force for Compliance, 1994; United States General Accounting Office [USGA], 1995). Adverse drug reactions account for approximately 17% of hospital admissions for elderly individuals, almost six times more than for the general population (USGA, 1995), and is estimated to be the fourth to sixth leading cause of death (Lazarou, Pomeranz, & Corey, 1998). Failing to take medications properly is estimated to cost $25 billion annually and result in 10% of nursing home admissions, costing $5 billion a year (The Task Force for Compliance, 1994). Although prescriber errors and idiopathic adverse drug reactions are a large component of medication related problems in active older adults, interactions of medications caused by errors in self-management of medicines contribute as well.
Problems in self-management of medicines resulting in interactions of OTC and prescription drugs among older adults exist for many reasons. Older adults' chronic conditions often require multiple prescription medications; their drug metabolism is more variable than younger individuals'; and they are often less able to hear, read, or understand oral and written instructions (Gazmararian et al., 1999; HanIon et al., 1992; Pollow, Stoller, Forster, & Duniho, 1994; Wallsten et al., 1995).
Other problems arise from interactions with alcohol and OTC agents. Studies of alcohol use among elderly individuals indicate approximately 65% self-report use of alcohol on a regular basis (Forster, Pollow, & Stoller, 1993; LisanskyGomberg, 1995 Moore, Hays, Greern dale, Damesyn, & Reuben, 1999). Adams (1995) found 38% of 311 residents of retirement communities responding to a m survey reported using both alcohol and a "high-risk" medication likely to interact with alcohol.
Studies of OTC medicine indicate approximately 50% of adults older than 65 regularly use OTC pain relievers and vitamins, 23% regularly use antacids, and 10% regularly use cold remedies or antihistamines (Stewart, 1991). The current spate of prescription to OTC switches, especially of pain relievers, antacids, acid reducers (H2 blockers), and antimstamines, is of particular concern because these agents have potentially adverse interactions with other medications and alcohol (Honig & Gillespie, 1995; Manasse, 1995; The Task Force for Compliance, 1994).
The increased availability of OTC medications used for ailments previously treated with prescription medications makes consumer understanding of drug effects and their interactions more important. A cross-sectional personal interview survey of high-functioning elderly individuals found they had significandy less understanding of the function and interactions of OTC medications compared to prescription medications (Wallsten et. al, 1995). Pollow et al. (1994) found 65% of a sample of 667 individuals older than 65 who were managing their own health reported at least one prescription-OTC drug or drug-alcohol combination with a possible adverse reaction.
They found 85% of those taking ulcer medications, 72% of those taking anticoagulants, and 28% of those taking antihypertensives were selfmedicating with OTC non-steroidal anti inflammatory drugs (NSAIDs). Of the potenrial interactions identified, 84% involved OTC NSAIDs. These examples illustrate how the growing access to and advertisement of OTC drugs increases thei use by independent older adults to treat minor, but chronic, problems. Unfortunately, the access and use, while giving indivia* uals more choice and opportunity for self-management, fosters secondary but serious and untoward outcomes.
Community health nurses (visiting nurses or local visiting nurses association [VNARNs]), primary care nurses, and advanced practice nurses (APRNs) have the opportunity to educate older adults about interactions arising from self-medication practices because these nurses care for individuals in the home, at community blood pressure screenings, and in community clinics. The purpose of this study was to assess the knowledge and self-efficacy of community nurses related to selected OTC-prescription interactions. Results of this study may assist educators in developing continuing education programs on self-medication practices and drug interactions in older adults for community nurses.
Increased knowledge and actual cognitive skill are traditional measures of educational interventions. Knowledge is also a prerequisite for performance of many health promotion behaviors. Knowledge alone, however, is not sufficient to explain or ensure behavioral performance.
SELF-EFFICACY OF COMMUNITY HEALTH NURSES CONCERNING OTC-RX INTERACTIONS
Self-efficacy, or the perception of ability to successfully complete a task, has been shown repeatedly to offer explanation of performance of behaviors beyond knowledge alone (Bandura, 1997; Strecher, DeVellis, Becker, & Rosenstock, 1986). It is a construct central to Bandura's Social Cognitive Theory and is related to whether an individual attempts tasks, persists, and achieves successful completion (Bandura, 1977; 1986; 1997). Investigators have found small to modest correlations between self-efficacy and measures of knowledge for health related tasks, suggesting each cognitive construct measures a separate component (Murdock & Neafsey, 1995; Neafsey, 1997; 1998). Such findings have been repeatedly interpreted to mean both knowledge and self-efficacy are important and different cognitive precursors of behavior (Bandura, 1997; Murdock & Neafsey, 1995; Neafsey, 1997, 1998; Strecher et al, 1986).
The knowledge and self-efficacy instruments used to survey community health nurses were based on the content of an interactive computer education program on interactions of prescription drugs with OTC agents and alcohol for older adults (Neafsey, Strickler, Shellman & Padula, 2001). The Personal Education Program (PEP) (Neafsey & Strickler, 1999) is loaded on large screen notebook computers equipped with infrared touchscreens. The PEP is designed for delivery to older adults by community health nurses caring for older adults in the home, and in such places as health care facilities, blood pressure clinics, and senior centers. The PEP content - which focuses on interactions of antihypertensives and anticoagulants with OTC pain relievers, nutrition supplements, antacids, acid reducers, and alcohol - provided the initial guide for item generation.
KNOWLEDGE OF OTC-Rx INTERACTIONS BY COMMUNITY HEALTH NURSES
KNOWLEDGE OF OTC-RX INTERACTIONS BY COMMUNITY HEALTH NURSES
Serf -efficacy Measure
An item pool of 21 behavioral, task-specific statements was generated using the typical approach for developing self-efficacy instruments (Bernal & Froman, 1987; Froman & Owen, 1989; 1991; Murdock & Neafsey, 1995). Following standard procedures for item review, a panel of three expert judges evaluated the item pool for content validity (Grant & Davis, 1997). The resulting 13item instrument was pilot tested with 134 volunteers recruited from local senior centers.
Data from pilot testing was subjected to a principal factor analysis (PFA) to study the factor structure underlying responses (Ferketich & Müller, 1990; Tabachnick & Fidell, 1996). The structure of the self-efficacy measure was found to be uni-dimensional. Therefore, a single internal consistency estimate for the scale was determined (Cronbach's alpha estimate = .95). Item loadings on the single factor solution were all greater than .63.
The self-efficacy instrument was administered to 31 nurses enrolled in a graduate primary care nursing course and then again 1 month later without intervention. The test-retest reliability estimate for the self-efficacy instrument was .84 (p «s .001). The Cronbach's alpha estimate was .92 on the first administration and .89 on the second administration. A PFA forced with a one-factor solution produced item loadings that were all greater than .57. These psychometric data support use of the self -efficacy instrument with a community-nursing sample.
Objective Measure of Knowledge
An initial pool of 27 multiplechoice knowledge questions was written based on the PEP content outline. The questions test knowledge and procedural information (Gagne & Glaser, 1987). Knowledge questions were built on examples of actual drug use, and test both knowledge and application levels of Bloom's taxonomy of the cognitive domain (Bloom, 1956). Items include short scenarios presenting potential interactions in a realistic, interesting setting (Neafsey, 1997; 1998). Each item has one correct response and three distracters based on common misconceptions about OTC medicines and alcohol. Content validity was assessed and a pool of 25 items was pilot tested.
Difficulty and discrimination indices were used to select the most content valid set of 20 items, which were then revised to improve clarity and retested to produce the final item pool of 17 questions. The Cronbach's coefficient alpha for internal consistency was .68 for the 31 nurses in the graduate course. The test-retest reliability estimate was .73 (p 5S .001).
Administration of Knowledge and Self-efficacy Instruments
Three convenience samples of community health nurses were recruited to complete the knowledge and self-efficacy instruments. The first was a sample of 20 experienced nurses working for a VNARN. The second was a sample of 20 BSN senior nursing students (graduate nurses [GNs]) completing their community health clinical with the VNARNs. The third was a sample of 31 nurses enrolled in the second semester of a graduate program training APRNs in primary care.
The BMDP (SSPS, Chicago, IL) statistical package (Dixon, 1990) was used for data analysis. Both univariate and multivariate data screening techniques were used and data were discarded if indicated as invalid multivariate outliers. Missing data at the item level were inputted with regressed scores from available variables. In any instance of 30% or more missing data, casewise deletion occurred.
TEACHING POINTS ABOUT OVER THE COUNTER (OTQ AND PRESCRIPTION DRUG INTERACTIONS
Analysis of variance (ANOVA) with one between-subjects factor (training) was used. Correlations between knowledge and SE scores were examined. The Student-Newman Keuls multiple range test was used for post-hoc analyses.
Table 1 lists the SE scores for the community health nurses. No significant difference existed in overall mean SE scores among VNARNs, GNs, and APRNs (F[Iy 67] = 1.57,/p = .22). Mean SE scores were in the "more or less sure" (3) to "very sure" (4) range indicating moderate SE related to OTC-prescription interactions.
Mean knowledge scores significantly differed among the community health nursing groups (F[2> 67] = 3.57, p = .03). Post-hoc analysis with the Student-Newman Keuls multiple range test showed the VNARNs had a significantly greater knowledge score [58.55 (SD = 13.18)] than the APRNs [49.4 (SD = 13.24)], /> = .017. Overall mean SE was not significantly correlated with mean knowledge scores for any of the community health nursing groups.
The knowledge items are paraphrased in Table 2 and the percentage of nurses from each group choosing each distracter given. The community health nurses in this study have several misconceptions about interactions of prescription and OTC drugs and alcohol. Although the results from this small convenience sample can not be generalized, the data can guide the development of teaching points for education programs aimed at community health nurses (Sidebar).
Antacids do not protect the stomach from pain relievers and alcohol When given a scenario in which an individual takes an aspirin right before consuming an alcoholic drink, 30% of the VNARNs and 27% of the APRNs thought the individual should take an antacid to protect the stomach (Question 1). In a similar scenario in which an individual takes an acid reducer such as Cimetidine (e.g., Tagamet) before consuming alcohol (Question 2), 15% of VNARNs, 10% of GNs, and 17% of APRNs thought the acid reducer would protect the stomach from alcohol. When presented with a scenario in which an individual takes an antacid with each dose of ibuprofen, 30% of VNARNs, 20% of GNs, and 43% of APRNs thought the antacid would lower the risk of stomach bleeding, and 30% of VNARNs, 40% of GNs, and 30% of APRNs thought the antacid would help prevent a stomach ulcer (Question 3).
Many older adults self-medicate osteoarthritis pain with OTC NSAIDs, even though inflammation is not characteristic and acetaminophen is recognized as the drug of choice in treating osteoarthritis (Bradley & Brandt, 1991; Williams et al., 1993). Gastric ulceration may be insidious in people using analgesics until a major bleeding episode occurs. The NSAIDs can damage the mucosal barrier by direct contact, but the major mechanism is a systemic inhibition of prostaglandins controlling gastric mucus and bicarbonate production. All OTC NSAIDs can cause gastric bleeding.
Attempts to counteract the ulcerogenic effect of NSAIDs by pre-medicating with antacids or OTC acid reducers (H2 antagonists) increases the older adult's risk of hospitalization for serious gastrointestinal bleeds (Singh et al., 1996). Antacids and acid reducers do not prevent NSAID induced gastric ulcers. In a study by Sievert, Stern, Lambert, and Peacock (1991), participants receiving a magnesium-aluminum antacid (Maalox) to prevent NSAID injury from naproxen had a significantly greater number of gastric erosions than did those with placebo plus naproxen. Limiting NSAID use is the only practice that can decrease the risk of NSAID induced gastric damage (Singh, 1998).
Antacids and calcium supplements should be taken 2 hours apart from other medicines. When asked the best time to take an antacid or calcium supplement (Question 4), 15% of VNARNs, 35% of GNs, and 30% of APRNs thought it should be taken at the same time or within a half hour of other medicines. When given a scenario of an individual taking an antacid at the same time as a coated aspirin (e.g., Ecotrin) (Question 5), 80% of GNs, but only 55% of VNARNs and 57% of APRNs knew antacids would dissolve the protective coating on the aspirin.
Enteric coatings dissolve in an alkaline pH. Taking calcium supplements or antacids with enteric-coated medications such as coated aspirin, erythromycin, or bisacodyl (e.g., Dulcolax) can result in gastric irritation. Calcium supplements and antacids can also reduce the absorption of medications such as levothyroxine, digoxin, phenytoin and ciprofloxacin, and nutrients such as iron, zinc, vitamin B12, and thiamin. Calcium supplements and antacids should be taken at least 2 hours apart from other medicines and nutrients (D'Arcy & McElnay, 1987).
Aspirin and acid reducers can increase the bioavaiUbility of alcohol Although 90% of GNs knew aspirin taken with alcohol increases the amount of alcohol entering the blood, only 65% of VNARNs and 43% of APRNs knew this (Question 1). Although 80% of GNs knew acid reducers have the same effect (Question 2), only 30% of VNARNs and 20% of APRNs did.
Aspirin (but not other NSAIDs) and H2 antagonists increase the bioavailability of alcohol by inhibiting gastric alcohol dehydrogenase (GAD) and increasing gastric emptying. Individuals taking aspirin (including low-dose aspirin, baby aspirin, or Pepto Bismol) or H2 antagonists within 2 hours of drinking alcohol will have higher blood alcohol levels and will increase their risk of alcoholassociated injuries (Amir, Anwar, Baraona, & Lieber, 1996; Baraona, Gentry, & Lieber, 1994; Caballería, 1991; Roine, Gentry, & HernandezMunoz, 1990). This interaction may be greater in men because they have higher GAD levels than women. Individuals who drink alcohol should not pre-medicate with H2 antagonists or medicine containing aspirin.
Ibuprofen and other NSAIDs increase blood pressure and counteract antihypertensives. Although 80% of VNARNs and 73% of APRNs selected acetaminophen as the best pain reliever for someone taking an antihypertensive, only 20% of GNs did (Question 4). However, given a scenario in which an individual on antihypertensive therapy uses Ibuprofen four times per day, only 40% of VNARNs and 40% of GNs knew blood pressure would increase, but 67% of APRNs knew (Question 7).
Chronic NSAID use (including OTC doses) increases blood pressure in both normotensive and hypertensive individuals not undergoing pharmacotherapy. Additionally, NSAID use has been found to counteract the antihypertensive effects of thiazide diuretics, beta-blockers, alpha-blockers, and angiotensin-converting enzyme inhibitors (Espino & Lancaster, 1992; Houston, 1991; Johnson, 1997; Polonia, 1997; Pope, Anderson, & Felson, 1993). Individuals with hypertension should be encouraged to use acetaminophen for pain and fever.
Alcohol can increase blood pressure. Eighty-five percent of VNARNs, 90% of GNs, and 73% of APRNs (Question 8) knew the relationship of alcohol use and blood pressure. Alcohol has a pressor effect when more than 1 oz. of alcohol is consumed per day (e.g., one "standard drink'' or the amount in 2 oz. 100 proof whiskey, 8 oz. of wine, 24 oz. of beer). Individuals with hypertension should be counseled to limit their alcohol intake to one standard drink per day (Maheswaran, Gill, Davies & Beevers, 1991; World Hypertension League, 1991).
Acetaminophen and ibuprof en (and other NSAIDs) can damage the kidneys. Only 25% of VNARNs, 20% of GNs, and 17% of APRNs knew any non-prescription pain reliever could damage the kidneys (Question 9).
The NSAIDs block intrarenal cyclooxygenase and suppress prostaglandin synthesis. Renal prostaglandins play a minor role in normal renal homeostasis. However, in individuals with decreased glomerular flow and pressure (e.g., congestive heart failure, age-related renal impairment, diuretic treated volume depleted hypertensives), prostaglandins are crucial in maintaining renal function. Use of NSAIDs by such individuals may result in acute renal failure (Bakris & Kern, 1989; Lamy, 1986).
Nephrotoxicity from acetaminophen (including doses lower than those that cause hepatotoxicity) is less common (Sandler et al., 1989). Patients with renal impairment should take acetaminophen only with careful monitoring by a health care provider. New OTC labels on analgesics mandated by the U.S. Food and Drug Administration carry a warning concerning possible kidney damage (2002).
Over-the-counter Cimetidine, NSAIDs, and acetaminophen can cause bruising and bleeding in individuals taking warfarin (Coumadin). When presented with a scenario in which an individual using Coumadin begins to self-medicate with OTC Cimetidine (e.g., Tagamet) daily, only 30% of VNARNs, 45% GNs, and 37% of APRNs knew the combination might cause bruising and bleeding (Question 10). The community nurses were more aware of the interaction of ibuprofen and Coumadin (Question 11). Eighty-five percent of VNARNs, 95% of GNs, and 70% of APRNs knew frequent use of ibuprofen would result in an increased risk of bruising and bleeding in someone taking Coumadin. Only 25% of VNARNs, 40% of GNs, and 43% of APRNs knew taking acetaminophen four times a day can cause bleeding in the brain (Question 12).
Cimetidine inhibits hepatic metabolism of many drugs prescribed to elderly individuals including warfarin, propranolol, nifedipine, theophylline, phenytoin, and lovostatin. Individuals on warfarin should be cautioned against use of Cimetidine and counseled to use famotidine (Pepcid) if they must use an acid reducer because it does not inhibit hepatic drug metabolizing enzymes.
Because all H2 antagonists reduce gastric acid production, older adults should be cautioned that chronic use of these agents may decrease absorption of vitamin B12, iron, zinc, and thiamin that depend on gastric acid for maximal bioavailability. Gastric acid provides a first defense against infection. Chronic reduction in gastric acid may increase risk of gastrointestinal infection, particularly in older adults with an age-related decline in immune function (Goodwin & Burns, 1991).
The NSAIDs displace warfarin from binding sites on plasma proteins, thus increasing the warfarin-free fraction (Wells, 1994). This can increase the International Normalized Ratio (INR), and lead to bruising and bleeding. Chronic use of high dose acetaminophen also increases the INR in individuals taking warfarin. The dose response of acetaminophen and increased INR occurs at doses greater than six regular-strength tablets per week. Individuals taking the maximum recommended dosage of acetaminophen per week (i.e., 4 per day or 28 per week) have a 10-fold risk of an INR over 6 (Hylek, Heiman, Skates, Sheehan, & Singer, 1998) when a target INR between 2.0 and 3.0 is recommended for most indications (Knies, 1999). An INR greater than 6 is associated with intracranial hemorrhage. Acetaminophen remains the drug of choice for fever and pain in individuals on warfarin therapy, but they should be counseled to limit their intake to six or fewer regular strength tablets per week unless INR is carefully monitored.
Heavy alcohol use with acetaminophen can damage the liver. Eighty-five percent of the VNARNs, 80% of the GNs, and 93% of the APRNs (Question 13) knew about this interaction. However, it still bears discussion in any education program on interactions of prescription drugs with OTC drugs and alcohol.
Normally, a compound called glutathione combines with acetaminophen metabolites and detoxifies them. Chronic alcohol ingestion induces hepatic enzymes and leads to an increased production of toxic acetaminophen metabolites. Thus, the glutathione is depleted and irreversible hepatotoxicity results (Rex & Kumar, 1992; Zimmerman & Maddrey, 1995).
Over-the-counter agents, such as zinc supplements, can damage the stomach. Sixty percent of VNARNs and 65% of GNs, but only 47% of APRNs (Question 14) knew this interaction. Many older adults selfmedicate with zinc because of its purported roles in immunity and in retarding macular degeneration (Cetaruk & Aaron, 1994; Rosenberg, 1990; Weiter, 1988). Zinc may be ulcerogenic; however, when taken in amounts greater than three times the recommended daily allowance (Weiter, 1988). Other ulcerogenic OTC agents include nicotinic acid and nicotine (including nicotine patches and gum) (Leung, 1994). Gingko biloba inhibits platelet-activating factors and can cause gastric irritation, thereby indirecdy contributing to gastric bleeding in individuals taking warfarin, aspirin, or any ulcerogenic agent (Williamson & Wyandt, 1998). Because data on interactions of OTC nutritional and herbal supplements with medications is limited, it is prudent for older adults at risk for gastric ulceration (e.g., those using warfarin, NSAIDs, alcohol, cigarettes, nicotine) to avoid OTC agents shown to be ulcerogenic.
In light of the increasing availability and use of OTC medications by older adults, the need for monitoring, education, and other interventions to inform older adults of potential drug interactions is most important. Community health nurses have an ideal opportunity to educate older adults about OTC drug interactions at the points of prescribing (e.g., in the health care provider's office), monitoring (e.g., at home visits, blood pressure clinics, wellness centers), and other community-focused health promotion activities. Community health nurses are frequently the main source of an older adult's health education. Therefore, accurate knowledge about OTC drug interactions is essential.
Even though the results from this small convenience sample are not generalizable, the data suggest community health nurses have several misconceptions related to OTC medications and would benefit from OTC-interaction continuing education programs. With accurate knowledge on the nine points discussed in this article, community health nurses could provide support, additional information, and individual counseling to assist older adults and their caregivers to better manage their medications.
Consequently, older adults will be empowered to make informed decisions related to the use of OTC medications and will make behavior changes to improve their quality of life. Moreover, by implementing educational interventions at the professional level and with clients, serious interactions of OTC agents with prescription medications may be prevented. Improved health and well being of the older population may result
Community nurses interested in using Preventing Medicine Conflicts with their clients may obtain a copy of the software from the first author by sending $15 for shipping and handling to the University of Connecticut School of Nursing.
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SELF-EFFICACY OF COMMUNITY HEALTH NURSES CONCERNING OTC-RX INTERACTIONS
KNOWLEDGE OF OTC-Rx INTERACTIONS BY COMMUNITY HEALTH NURSES
KNOWLEDGE OF OTC-RX INTERACTIONS BY COMMUNITY HEALTH NURSES
TEACHING POINTS ABOUT OVER THE COUNTER (OTQ AND PRESCRIPTION DRUG INTERACTIONS