Research in Gerontological Nursing

Research Brief 

Variations in Patterns of Care Activities for Nursing Home Residents with Heart Failure

Jill R. Quinn, PhD, RN, CS-ANP, FNAP, FAANP, FAHA; Irena Pesis-Katz, PhD; Dana B. Mukamel, PhD

Abstract

Early clues of change in heart failure (HF) status, such as weight gain or reduced exercise tolerance, may be missed by caregivers in nursing homes (NHs) since daily weight measurement and functional assessments may not be performed routinely. These factors are likely to contribute to a delay in non-emergent care for the resident. The purpose of this study was to examine patterns of care activities provided in the NH setting to residents with HF and document variations in these care patterns across a random national sample of NHs. Care activities performed daily within a large proportion of NHs for residents with HF were assessment for changes in HF symptoms (94%), changes in mental status (91%), and changes in swelling/edema (85%). There was wide variation in care patterns. Not all evidence-based guidelines for HF care and monitoring were followed in the NH setting, which could affect hospitalizations and other outcomes.

Abstract

Early clues of change in heart failure (HF) status, such as weight gain or reduced exercise tolerance, may be missed by caregivers in nursing homes (NHs) since daily weight measurement and functional assessments may not be performed routinely. These factors are likely to contribute to a delay in non-emergent care for the resident. The purpose of this study was to examine patterns of care activities provided in the NH setting to residents with HF and document variations in these care patterns across a random national sample of NHs. Care activities performed daily within a large proportion of NHs for residents with HF were assessment for changes in HF symptoms (94%), changes in mental status (91%), and changes in swelling/edema (85%). There was wide variation in care patterns. Not all evidence-based guidelines for HF care and monitoring were followed in the NH setting, which could affect hospitalizations and other outcomes.

The prevalence of heart failure (HF) in nursing home (NH) residents is approximately 20%, which is much higher than the 2.6% found in the general population (Daamen, Schols, Jaarsma, & Hamers, 2010; Roger et al., 2011). Hospitalization of people with complex care needs can be costly, estimated at $32.9 billion for HF care in 2010 (Lloyd-Jones et al., 2009), and outcomes are often poor for older adult patients, who have other comorbidities (Levine, Sachs, Jin, & Meltzer, 2007). There are approximately 1.5 million NH residents in the United States, most of whom are 65 and older. With the dramatic growth of the older adult population in the past decade, the quality of long-term care has become increasingly important (Fang, Mensah, Croft, & Keenan, 2008).

Improvements in NH processes of care, such as increased frequency of skilled nursing observations, are associated with reduced hospitalizations and mortality. Researchers found that providing skilled nursing observations more than once per shift reduced the odds of dying by 70% (Harrington, 2008; Hutt, Frederickson, Ecord, & Kramer, 2003; Lester, Stefanacci, & Chen, 2009). Provider adherence to evidence-based guidelines developed by the American College of Cardiology (ACC) and American Heart Association (AHA) and individual focus on monitoring symptoms, dietary adherence, and medications have been demonstrated to improve outcomes in the community-dwelling HF population (Hernandez et al., 2010; Jessup et al., 2009; Riegel et al., 2009). However, little is known about adherence to these guidelines in NHs. The patterns of care for NH residents with HF and how these patterns vary across different facilities have not been reported.

Recently, there has been a paradigm shift in considering the best approach for cardiac care of older adults with greater emphasis on age-related risks and goals. In comparison with community-dwelling older adults, most NH residents tend to be older, sicker, with more comorbidities (Forman et al., 2011). A NH’s ability to care for a resident within the facility is affected by NH structure and availability of resources (Grabowski, Stewart, Broderick, & Coots, 2008), but NH residents with a known diagnosis of HF can avoid hospitalization if their condition is well managed at the NH through certain HF management activities.

NH residents are dependent on their health care providers to recognize changes in their health status. Symptoms and signs of worsening HF (e.g., fatigue, decreased functional abilities, shortness of breath, increased confusion) are often misinterpreted as normal changes of aging (Yamasaki et al., 2003). Early clues of change in HF status, such as weight gain or reduced exercise tolerance, may be missed by care providers in NHs since daily weight measurements and functional assessments may not be performed routinely (Harrington, 2008; Hutt et al., 2003; Lester et al., 2009). Readmission rates from skilled nursing facilities have been reported to be as high as 30%, with 3.7% reported to be avoidable conditions (Centers for Medicare & Medicaid Services [CMS], 2010; Jacobs, 2011). Less-frequent assessments are likely to contribute to a delay in non-emergent care for residents (manageable in the NH setting) and result in progressive deterioration in HF, ultimately requiring hospitalization. Many unnecessary hospitalizations of older adults are attributed to HF patients’ and care providers’ inability to recognize and respond to early signs of decompensating HF (Quinn, 2008; Riegel et al., 2009).

The purpose of this study was to examine, in a random national sample of NHs, the care activities provided to residents with a diagnosis of HF, and document variations in their care patterns. Underpinning this exploratory descriptive study is the cumulative body of literature and evidence comprising the ACC/AHA guidelines. Using this framework, this study aimed to examine the extent to which these guidelines are reported to be followed in the NH setting. More specifically, we looked at whether NHs were providing all recommended evidence-based care activities for residents with HF at the recommended frequency.

Method

Sample

In 2010, there were 15,682 NHs in the United States (CMS, 2010). We excluded NHs with 30 or fewer beds, as they may have fewer resources to provide care to their residents. Since a NH’s hospital affiliation increases the probability of hospital admission and may include shared resources with the hospital to manage HF, we further excluded facilities with a hospital affiliation. Applying these exclusions resulted in a population of 14,193 NHs. We randomly sampled from these NHs, using the random number generator in SAS version 9.1 to identify our pilot sample of 50 NHs. The final study sample of respondents was a sufficient size to show any variability in NHs’ care patterns for residents with a known diagnosis of HF within a reasonable time frame for data collection.

Survey Instrument

The survey consisted of 23 questions, some with multiple levels. The general topics covered in the survey were overall resident care planning activities, provider resources, facility onsite resources, within-facility decision making for hospitalization, care activities specific to HF, and background demographics of the person completing the survey. The survey was designed to learn about specific protocols or patterns of care delivered to NH residents with HF based on the current evidence-based guidelines (Jessup et al., 2009) and to examine variations in resources, as well as care activities at the facility. In this article, we focus on HF care activities. Evidence-based guidelines from the ACC/AHA include assessing for medication taking, symptom monitoring, dietary adherence, fluid restriction, alcohol restriction, weight loss/gain, exercise, and smoking cessation (Jessup et al., 2009). These recommended assessment activities were used to develop the survey questions, which focus on the type of care activities provided and the frequencies of performing these activities for residents with a diagnosis of HF in the NH. These questions targeted all residents with a known diagnosis of HF, regardless whether it is a primary diagnosis.

The survey was first tested for face validity with two focus groups, each with two to three retired Directors of Nursing (DONs). Three of the DONs had retired within the past 5 years and one 15 years ago. Two of the DONs (including the one who was retired the longest) worked with another investigator collecting NH data through 2004. That meant they were in NHs across the region on a daily basis, interacting with the DONs and nursing staff and reviewing charts. Both focus groups and our survey participants identified DONs as the best person within the NH to answer these questions. This was further supported by prior studies examining NHs’ resident care (Buchanan et al., 2006; Lester et al., 2009; Smith, Ghezzi, Manz, & Markova, 2008). Content validity was determined by a cardiac nurse practitioner, cardiologist, and general medicine physician. The survey instrument showed good internal consistency between all the HF-related items, with a Cronbach’s alpha coefficient of 0.79 in this study.

Survey Administration Procedure

The university institutional review board for human subjects protection approved this study. The investigator-developed survey was mailed to the DONs of the randomly selected 50 NHs across the United States. We administered the survey in three waves over a 2-month period of data collection, starting on November 3, 2009. The first two waves included mailings of a letter with instructions to complete the survey. The surveyed DONs were given the choice of completing the survey online using SurveyMonkey™ or returning the survey in a self-addressed, stamped envelope. The third wave included follow-up telephone calls that were placed to the DONs who had not responded to the first two waves of mailings. We offered them the opportunity to complete the survey by telephone or online. The data collection process ended on January 7, 2010.

Statistical Analysis

We used descriptive statistics to summarize survey responses and responders’ characteristics. All analyses were performed using SAS version 9.1.

Results

The response rate to our survey was 66%, resulting in a final sample of 33 NHs. The first two waves generated 15 responses and the third wave an additional 18 responses. We examined NHs’ and DONs’ characteristics, as well as care patterns and available resources. We found that all of the DON survey respondents (N = 33) were women, and 73% had more than 10 years of experience in the NH working environment. The race distribution of DONs was 88% Caucasian, 6% African American, and 6% Other.

Table 1 provides a description of facility characteristics for all U.S. NHs meeting the inclusion criteria for random sampling and the respondent and non-respondent NHs. Twenty-eight (84.8%) respondent NHs were for profit. Seventeen (51.5%) were part of a NH chain. Average size of the respondent NHs was 107 (SD = 61.1) beds, and the average number of residents was 88.79 (SD = 56). We also found that, on average, the respondent NHs had 0.53 (SD = 0.29), 0.78 (SD = 0.21), and 2.36 (SD = 0.48) hours per resident per day for RNs, licensed practical nurses/licensed vocational nurses, and certified nursing assistants, respectively.

Characteristics of U.S. Nursing Homes (NHs) Meeting Inclusion Criteria, Responders, and Non-Responders

Table 1: Characteristics of U.S. Nursing Homes (NHs) Meeting Inclusion Criteria, Responders, and Non-Responders

HF was reported as one of the top five most common reasons for resident hospitalizations. Only 11 (33.3%) of the NHs had a nurse practitioner available onsite, and 10 (30.3%) and 5 (15.1%) had a medical director and a staff physician available, respectively. However, most respondents (93.9%) reported having on-call services by medical care providers available. Only 4 (12.1%) respondents reported having a clinical laboratory onsite, and only 3 (9.1%) had radiology and pharmacy services available. Almost all (96.9%) surveyed NHs could provide oxygen onsite, approximately 25 (75.8%) of NHs could provide intravenous medications or draw blood for laboratory tests onsite, and 21 (63.6%) could perform stat blood tests; however, less than half (48.5%) of NHs could perform stat x-rays onsite, and only 7 (21.2%) could administer defibrillation in the facility (Table 2).

Reported Onsite Available Clinical Services and Activities (N = 33)

Table 2: Reported Onsite Available Clinical Services and Activities (N = 33)

No NHs performed all recommended activities at the recommended frequencies. The Figure lists the frequencies of care activities performed for NH residents with HF across the respondent NHs. Care activities performed daily by a large proportion of NHs for residents with HF were assessing changes in symptoms (94%), assessing changes in mental status (91%), and assessing changes in swelling/edema (85%). Less-common activities performed on a daily basis across NHs were measuring fluid intake and output (48%), assessing lungs (48%), and measuring weight (15%).

Reported frequencies of care activities for nursing home residents with heart failure.Note. ADLs = activities of daily living; BP = blood pressure; HR = heart rate; I & O = intake and output.

Figure. Reported frequencies of care activities for nursing home residents with heart failure.Note. ADLs = activities of daily living; BP = blood pressure; HR = heart rate; I & O = intake and output.

A wide variation in frequencies of resident care activities was reported across NHs in the sample. Frequency also varied within NHs; that is, NHs that reported frequent performance of one care activity did not necessarily report frequent performance of other care activities.

Discussion

We found wide variation in care patterns for NH residents with a diagnosis of HF in a small but representative sample of NHs. Even though the majority of respondent NHs reported monitoring of symptoms, assessing activity tolerance, assessing for signs of swelling, and assessing changes in mental status—as recommended by guidelines (Jessup et al., 2009)—the frequency of these activities largely varied across NHs.

Several key care activities recommended to be performed daily, such as weight measurement and sodium intake monitoring, if reported, were performed less frequently. Weighing was most frequently done on a weekly basis and not daily, as recommended by guidelines. Hence, an increase of 2 to 3 pounds over 2 to 3 days as an indicator of worsening HF would not be recognized. Hutt, Ecord, Eilertsen, Frederickson, and Kramer (2002) noted that the most prevalent sign of HF among residents admitted to the emergency department were hypoxemia, bradycardia or tachycardia, and altered sensorium. In our sample, heart rate and blood pressure were measured daily in only approximately 60% of the NHs surveyed, although mental status (sensorium) was assessed daily in the majority of the NHs.

Variations in performance of some resident care activities and assessments can probably be attributed to variations in state and federal NH requirements and regulations (U.S. Department of Health and Human Services, Office of Inspector General, 2001). According to federal regulations, certain assessments (e.g., change in ADLs) are required to be documented at various periods of time during the resident stay at the NH and often guide the individualized resident care plan within the facility. However, key HF care activities, such as weight measurement, are required generally only every 30 days (Harrington, 2008), and monitoring salt intake is generally not performed on a regular basis but done only when ordered. Performing these care activities more frequently, per the ACC/AHA guidelines, could perhaps avoid or delay hospitalization for residents with HF, but these guidelines may not be applicable to NH residents, as they have been primarily designed for community-dwelling HF patients. More research is needed to identify the care patterns for NH residents with HF that are most likely to reduce hospitalization and mortality.

Although more evidence is needed on the impact of full implementation of these guidelines on outcomes in NHs, implementation of recommended activities appears feasible. Martinen and Freundl (2004) tested an evidence-based HF protocol in a long-term care setting that targeted both NH and assisted living residents. The protocol included initiating a weight regimen for newly admitted residents with a HF diagnosis. Residents with HF were weighed three times per week, and if a 2-pound weight increase was noted, the resident was to be assessed by the nursing staff for evidence of HF-related symptoms (e.g., shortness of breath and presence of edema), per the protocol. The investigators reported that the increased nursing assessment was one of the most difficult areas of their protocol to implement. The nursing staff did not understand why they were monitoring the residents’ weight, how they needed to assess for the presence of symptoms, or how they needed to contact residents’ attending physician. After further staff education and reinforcement of the protocol, the frequency of these activities had improved at 6 months after implementation. However, only a small number (n = 9) of NH residents were included in that study, and the impact on outcomes such as hospitalization and mortality was not clearly identified.

Improvement in quality of care and a 30% reduction in rehospitalization of skilled nursing facility residents with HF has been demonstrated when partnerships are formed between the hospital and skilled nursing facility staff to enhance communication (Jacobs, 2011). Use of multidisciplinary teams of specialized providers has been proven effective in coordinating care in the outpatient setting, and this may prove effective in NHs as well (Naylor et al., 2004; Pressler, 2011; Stauffer et al., 2011).

Conclusion

Now that we have identified wide variation in the types and frequencies of care activities for residents with HF across different NHs and within the same NH across activities, the impact of this variation on resident outcomes needs further study. Identifying practices among NHs associated with best resident outcomes will determine the applicability of care guidelines developed for other populations. Further research can also explore how nursing home staffing and resident characteristics affect patterns of care and resident outcomes This, in turn, will guide the development of protocol-driven interventions to provide the best care for NH residents with HF and improve resident outcomes.

References

  • Buchanan, J.L., Murkofsky, R.L., O’Malley, A.J., Karon, S.L., Zimmerman, D., Caudry, D.J. & Marcantonio, E.R. (2006). Nursing home capabilities and decisions to hospitalize: A survey of medical directors and directors of nursing. Journal of the American Geriatrics Society, 54, 458–465. doi:10.1111/j.1532-5415.2005.00620.x [CrossRef]
  • Centers for Medicare & Medicaid Services. (2010). Nursing home compare. Retrieved from http://www.medicare.gov/NHCompare
  • Daamen, M.A., Schols, J.M., Jaarsma, T. & Hamers, J.P. (2010). Prevalence of heart failure in nursing homes: A systematic literature review. Scandinavian Journal of Caring Sciences, 24, 202–208. doi:10.1111/j.1471-6712.2009.00708.x [CrossRef]
  • Fang, J., Mensah, G.A., Croft, J.B. & Keenan, N.L. (2008). Heart failure-related hospitalization in the U.S., 1979 to 2004. Journal of the American College of Cardiology, 52, 428–434. doi:10.1016/j.jacc.2008.03.061 [CrossRef]
  • Forman, D.E., Rich, M.W., Alexander, K.P., Zieman, S., Maurer, M.S., Najjar, S.S. & Wenger, N.K. (2011). Cardiac care for older adults: Time for a new paradigm. Journal of the American College of Cardiology, 57, 1801–1810. doi:10.1016/j.jacc.2011.02.014 [CrossRef]
  • Grabowski, D.C., Stewart, K.A., Broderick, S.M. & Coots, L.A. (2008). Predictors of nursing home hospitalization: A review of the literature. Medical Care Research and Review, 65(1), 3–39. doi:10.1177/1077558707308754 [CrossRef]
  • Harrington, C.C. (2008). Assessing heart failure in long-term care facilities. Journal of Gerontological Nursing, 34(2), 9–14. doi:10.3928/00989134-20080201-10 [CrossRef]
  • Hernandez, A.F., Greiner, M.A., Fonarow, G.C., Hammill, B.G., Heidenreich, P.A., Yancy, C.W. & Curtis, L.H. (2010). Relationship between early physician follow-up and 30-day readmission among Medicare beneficiaries hospitalized for heart failure. Journal of the American Medical Association, 303, 1716–1722. doi:10.1001/jama.2010.533 [CrossRef]
  • Hutt, E., Ecord, M., Eilertsen, T.B., Frederickson, E. & Kramer, A.M. (2002). Precipitants of emergency room visits and acute hospitalization in short-stay Medicare nursing home residents. Journal of the American Geriatrics Society, 50, 223–229. doi:10.1046/j.1532-5415.2002.50052.x [CrossRef]
  • Hutt, E., Frederickson, E., Ecord, M. & Kramer, A.M. (2003). Associations among processes and outcomes of care for Medicare nursing home residents with acute heart failure. Journal of the American Medical Directors Association, 4, 195–199. doi:10.1016/S1525-8610(04)70345-X [CrossRef]
  • Jacobs, B. (2011). Reducing heart failure hospital readmissions from skilled nursing facilities. Professional Case Management, 16(1), 18–24.
  • Jessup, M., Abraham, W.T., Casey, D.E., Feldman, A.M., Francis, G.S., Ganiats, T.G. & Yancy, C.W. (2009). 2009 focused update: ACCF/AHA guidelines for the diagnosis and management of heart failure in adults: A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines: Developed in collaboration with the International Society for Heart and Lung Transplantation. Circulation, 119, 1977–2016. doi:10.1161/CIRCULATIONAHA.109.192064 [CrossRef]
  • Lester, P., Stefanacci, R.G. & Chen, D.G. (2009). Nursing home procedures on transitions of care. Journal of the American Medical Directors Association, 10, 634–638. doi:10.1016/j.jamda.2009.06.008 [CrossRef]
  • Levine, S.K., Sachs, G.A., Jin, L. & Meltzer, D. (2007). A prognostic model for 1-year mortality in older adults after hospital discharge. American Journal of Medicine, 120, 455–460. doi:10.1016/j.amjmed.2006.09.021 [CrossRef]
  • Lloyd-Jones, D., Adams, R.J., Brown, T.M., Carnethon, M., Dai, S., De Simone, G. & Wylie-Rosett, J. (2009). Heart disease and stroke statistics—2010 update. A report from the American Heart Association. Circulation. Retrieved from http://circ.ahajournals.org/content/121/7/e46.full.pdf+html. doi:
  • Martinen, M. & Freundl, M. (2004). Managing congestive heart failure in long-term care: Development of an interdisciplinary protocol. Journal of Gerontological Nursing, 30(12), 5–12.
  • Naylor, M.D., Brooten, D.A., Campbell, R.L., Maislin, G., McCauley, K.M. & Schwartz, J.S. (2004). Transitional care of older adults hospitalized with heart failure: A randomized, controlled trial. Journal of the American Geriatrics Society, 52, 675–684. doi:10.1111/j.1532-5415.2004.52202.x [CrossRef]
  • Pressler, S.J. (2011). Heart failure patients in skilled nursing facilities: Evidence needed. Circulation: Heart Failure, 4, 241–243. doi:10.1161/CIRCHEARTFAILURE.111.962258 [CrossRef]
  • Quinn, J.R. (2008). Recognition of worsening heart failure by chronic heart failure patients and their significant others prior to hospitalization [Abstract]. Journal of Cardiac Failure, 16(6), S95. doi:10.1016/j.cardfail.2008.06.266 [CrossRef]
  • Riegel, B., Moser, D.K., Anker, S.D., Appel, L.J., Dunbar, S.B., Grady, K.L. & Whellan, D.J. (2009). State of the science: Promoting self-care in persons with heart failure: A scientific statement from the American Heart Association. Circulation, 120, 1141–1163. doi:10.1161/CIRCULATIONAHA.109.192628 [CrossRef]
  • Roger, V.L., Go, A.S., Lloyd-Jones, D.M., Adams, R.J., Berry, J.D., Brown, T.M. & Wylie-Rosett, J. (2011). Heart disease and stroke statistics—2011 update. Circulation, 123, e18–e209. doi:10.1161/CIR.0b013e3182009701 [CrossRef]
  • Smith, B.J., Ghezzi, E.M., Manz, M.C. & Markova, C.P. (2008). Perceptions of oral health adequacy and access in Michigan nursing facilities. Gerodontology, 25, 89–98. doi:10.1111/j.1741-2358.2007.00202.x [CrossRef]
  • Stauffer, B.D., Fullerton, C., Fleming, N., Ogola, G., Herrin, J., Stafford, P.M. & Ballard, D.J. (2011). Effectiveness and cost of a transitional care program for heart failure: A prospective study with concurrent controls. Archives of Internal Medicine, 171, 1238–1243. doi:10.1001/archinternmed.2011.274 [CrossRef]
  • U.S. Department of Health and Human Services, Office of Inspector General. (2001). Nursing home resident assessment quality of care (Publication No. OEI-02-99-00040). Retrieved from http://oig.hhs.gov/oei/reports/oei-02-99-00040.pdf
  • Yamasaki, N., Kitaoka, H., Matsumura, Y., Furuno, T., Nishinaga, M. & Doi, Y. (2003). Heart failure in the elderly. Internal Medicine, 42, 383–388. doi:10.2169/internalmedicine.42.383 [CrossRef]

Characteristics of U.S. Nursing Homes (NHs) Meeting Inclusion Criteria, Responders, and Non-Responders

Sample NHs (N = 50)
NHs Meeting Inclusion Criteriaa (N = 14,193) Responders (n = 33) Non-Responders(n = 17)
Characteristic n (%) n (%) n (%)
For profit 10,323 (72.7) 28 (84.8) 11 (64.7)
NH part of a chain 7,942 (56) 17 (51.5) 10 (58.8)
Mean (SD) Mean (SD) Mean (SD)
Number of certified beds 111.9 (59.2) 107 (61.1) 115.3 (51.2)
Number of residents in NH 94.2 (54.8) 88.79 (56) 100.8 (44.8)
Number of RN hours per resident per day 0.67 (0.29) 0.53 (0.29) 0.62 (0.43)
Number of LPN/LVN hours per resident per day 0.84 (0.21) 0.78 (0.21) 0.78 (0.36)
Number of CNA hours per resident per day 2.42 (0.48) 2.36 (0.48) 2.16 (0.51)

Reported Onsite Available Clinical Services and Activities (N = 33)

Type of Service/Activity n (%)
Staff services
  On-call services 31 (93.9)
  Nurse practitioners 11 (33.3)
  Medical director 10 (30.3)
  Staff physician 5 (15.1)
  Physician assistants 4 (12.1)
Clinical services
  Clinical laboratory 4 (12.1)
  Pharmacy/pharmacist 3 (9.1)
  Radiology/x-ray machine 3 (9.1)
Clinical activities
  Provide oxygen 32 (96.9)
  Draw blood for laboratory tests 25 (75.8)
  Provide IV medications 25 (75.8)
  Perform stat blood tests 21 (63.6)
  Perform stat x-ray 16 (48.5)
  Administer defibrillation in the facility 7 (21.2)
  Perform a 12-lead ECG 6 (18.2)
Authors

Dr. Quinn is Associate Professor, and Dr. Pesis-Katz is Assistant Professor, University of Rochester, School of Nursing, Rochester, New York, and Dr. Mukamel is Professor, Department of Medicine, and Senior Fellow, Health Policy Research Institute, University of California, Irvine, Irvine, California.

The authors have disclosed no potential conflicts of interest, financial or otherwise.

Address correspondence to Jill R. Quinn, PhD, RN, CS-ANP, FNAP, FAANP, FAHA, Associate Professor, University of Rochester, School of Nursing, 601 Elmwood Avenue, Rochester, NY 14642; e-mail: jill_quinn@urmc.rochester.edu.

Received: November 01, 2011
Accepted: March 14, 2012
Posted Online: December 12, 2012

10.3928/19404921-20121204-02

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