The authors are with the Center for Health Outcomes and Policy Research, University of Pennsylvania School of Nursing, Philadelphia. Douglas M. Sloane is also with the Life Cycle Institute and Department of Sociology, Catholic University of America, Washington, DC. Linda H. Aiken is also with the Department of Sociology, University of Pennsylvania, Philadelphia.
Correspondence: Sean P. Clarke, PhD, RN, Center for Health Outcomes and Policy Research, University of Pennsylvania School of Nursing, 420 Guardian Dr, Philadelphia, PA 19104-6096 (e-mail: sclarke@nursing.upenn.edu).
ABSTRACT
Objectives. This study determined the effects of nurse staffingand nursing organization on the likelihood of needlestick injuriesin hospital nurses.
Methods. We analyzed retrospective data from 732 and prospectivedata from 960 nurses on needlestick exposures and near missesover different 1-month periods in 1990 and 1991. Staffing levelsand survey data about working climate and risk factors for needlestickinjuries were collected on 40 units in 20 hospitals.
Results. Nurses from units with low staffing and poor organizationalclimates were generally twice as likely as nurses on well-staffedand better-organized units to report risk factors, needlestickinjuries, and near misses.
Conclusions. Staffing and organizational climate influence hospitalnurses' likelihood of sustaining needlestick injuries. Remedyingproblems with understaffing, inadequate administrative support,and poor morale could reduce needlestick injuries.
INTRODUCTION
Exposures of health care workers to bloodborne pathogens throughaccidental contact with sharp instruments have been widely publicized,and the prevention and control of exposure to sharp instrumentsis a high-profile issue. Estimates from the University of Virginia'sExposure Prevention Information Network (EPINet) surveillancesystem for 1996 placed the number of the percutaneous injuriesto US health workers in that year at almost 600 000.1 In thelargest study of needlesticks to date based on nurse reports(as opposed to institutional surveillance), we reported a startlinglyhigh rate of nearly 1 injury per nurse-year using data froma national nurse survey in 1991.2 Because the potential consequencesof hepatitis B and C and HIV and AIDS infection are so severe,the relatively low rates of seroconversion after percutaneousinjuries—estimated at less than 0.5% for HIV—arenot particularly reassuring.3–5 Moreover, because thepersonal and professional consequences of needlestick injuriescan be devastating even when they do not result in infections,5needlestick and related injuries remain a very serious occupationalhealth concern for nurses and other health care workers.
The dominant perspective in the literature and in most agencyguidelines is that the transmission of bloodborne pathogensfrom patients to health care workers is largely preventablethrough the use of universal precautions and special equipment(primarily systems that resheathe needles after use and needlelessaccess devices). Exclusive reliance on these strategies is inadequate,however, for several reasons. First, the adoption of universalprecautions to date has been far from universal. Studies haveshown, for example, that nurse compliance with universal precautionsis affected by the availability of protective equipment, theperceived commitment of management to safety, and perceptionsregarding the interference of precautions with job performance.6,7Second, the adoption of needleless technology has been widespread,but it is unlikely that any technology can ever entirely removethe need for health professionals to handle bare needles andsharps. Third, awareness is increasing that needlestick accidents,like medical errors, complications, and other reportable incidentsin hospitals, may be related to organizational factors suchas staffing and the nurse practice environment as well as staffeducation and the types of equipment used.
Although many aspects of sharps injuries and body fluid exposureshave been extensively studied, Hanrahan and Reutter8 noted intheir review of the literature that an organizational perspectiveon this issue is needed. To our knowledge, little research hasbeen conducted to determine what factors produce variationsin needlestick injury rates across hospitals or hospital unitsand whether nurse staffing and organizational climate are importantdeterminants. Examining the organizational context of needlestickinjuries is particularly timely, given recent state and national initiatives to reduce bloodborne pathogen exposures by requiringthe use of specific types of devices in hospitals and separatebroader state initiatives mandating minimum staffing levelsin hospitals.
In our previous study of AIDS care provided in 20 hospitalsacross the United States, 1990–1991, we estimated the frequency of needlestick injuries to hospital nurses based on data from various sources.2 In addition to retrospective reportsfrom surveyed nurses regarding the number of times they wereinjured with a blood-contaminated needle in the prior month,we asked the same nurses to report needlesticks at the end ofevery shift they worked for 30 days (i.e., prospectively). Onthe basis of the prospective shift-based reports, we estimatedthat the rate of injuries to staff nurses was 0.8 per nurseper year. Prospective and retrospective rates were statistically indistinguishable. Our data also showed that only about 1 in 4 needlestick injuries were reported to hospital authorities. We also found that nurses who reported recapping needles were at heightened risk for injury and that nurses working in magnethospitals (3 of the 20 hospitals were known for having an especiallypositive working climate for nurses9) were at significantlyreduced risk for injury. The results reported in this articleextend the work of that study by exploring how risk factorsassociated with needlestick injuries and the relative frequencyof needlestick injuries among hospital nurses are related tothe staffing levels and organizational climates on the hospitalunits on which nurses work.
METHODS
Sample We analyzed data from a survey conducted in 1991 of nurses workingon 40 inpatient units in 20 general hospitals located in 11cities with high AIDS prevalence: New York, NY; Baltimore, Md;Boston, Mass; Chicago, Ill; Miami, Fla; Dallas, Tex; New Orleans,La; Atlanta, Ga; Philadelphia, Pa; San Francisco, Calif; andLos Angeles, Calif.10,11 In the parent study of hospital organizationand inpatient AIDS care, a purposive sample of 10 hospitalswas chosen from a national master list of institutions thathave specialized AIDS units with at least 10 beds. A matchedgroup of 10 hospitals in the same geographic areas but without specialized AIDS units was drawn on the basis of characteristicssuch as bed size, governance, and clientele served. Detailsare discussed in an earlier publication.10
In addition to instruments measuring the working climate inthe study hospitals and hospital units, the confidential, selfadministeredquestionnaire filled out by the nurses included items dealingwith exposures to sharps over the previous 1-month and 1-yearperiods.2 Of the 865 staff nurses permanently assigned to thestudy units who received the questionnaire, 762 returned it,and 732 questionnaires were usable. Additional prospective data dealing with exposures to sharps and near-miss injuries were collected from all nurses working on the study units (regular staff nurses and temporary nurses) at the end of each shift over two 1-month periods in late 1990 and early 1991. Reports were obtained for 12 349 (86%) of the total 14 379 shifts workedby 960 regular and temporary staff nurses. Because the retrospectivesurvey was conducted 2 months before the prospective portionof the study began, the periods of time and the injuries thatoccurred during the prospective and retrospective data collectiondid not overlap.
Measures Exposures to contaminated sharps. The nurses who completed our retrospective survey were asked whether they had ever been stuck with a needle or sharp objectcontaminated with blood. Those who responded affirmatively werethen asked how many times this had occurred and how many ofthe incidents had occurred in the past month.
The prospective portion of our data collection involved theuse of booklets containing a sufficient number of reportingforms (coupons) for a month of shifts. These coupon bookletswere distributed to staff and nonstaff nurses (both registerednurses and licensed practical nurses) on each of the study units.One coupon was filled out by each nurse at the end of each shiftworked and placed in a secure box on the study unit. Nursesindicated on each coupon whether they had incurred a needleor sharp injury, defined as "a puncture with a needle or sharpinstrument that is contaminated with blood," and whether theyhad had a "near-miss with a used needle or sharp" on that shift.
Staffing data. The number of full-time-equivalent registered nurse positions and the average daily patient census on each of the units for each day of the first month of the study period were determinedfrom administrative data provided by the managers on the nursingunits, including payroll sheets and patient assignment worksheets.Ratios of registered nurse positions to average daily patientcensus on each unit were calculated, cross-checked, and usedin the analyses later in this article. In the results presentedhere, lower-staffed hospital units had registered nurse–to–averagedaily patient census levels reflecting ratios of approximately1 nurse for every 10 or more patients on average.
Resource adequacy and nurse manager leadership. Resource adequacy and nurse manager leadership were drawn fromthe Revised Nursing Work Index, a battery of items that gaugenurses' perceptions of the presence of selected organizationalcharacteristics in their work setting. Details about the developmentof this tool, its psychometric properties, and its validationin successive studies by our team are available in another recentpublication.12 The Revised Nursing Work Index contains 49 itemsthat asks nurses to indicate, on a 4-point scale from "stronglyagree" to "strongly disagree," whether various features arepresent in their practice setting.
Three theoretically derived summary measures were initiallyconstructed from these items, and 6 empirically derived subscaleswere subsequently isolated with factor analytic techniques.13The resource availability and nurse manager leadership subscales(r = 0.63) used in the current analyses deal with unit-levelorganizational support for nursing practice and were thereforebelieved to be the most plausible correlates of needlestickrisk. Other subscales address factors such as the influenceof senior nurse executives and the quality of nurse–physicianrelationships. Resource adequacy was derived from 4 items thatdealt with nurses' perceptions of whether staffing was sufficientto accomplish the work to be done and to provide quality patientcare and whether they had enough time and opportunity to discusspatient care problems with other nurses. Nurse manager leadershipwas derived from 5 items that dealt with perceptions of thenursing unit manager's leadership and support of nurses' initiativeand decisionmaking. Cronbach s for these 2 subscales in thecurrent data were .83 and .81, respectively. Scores on thesesubscales provided by each nurse on a given nursing unit wereconsidered independent judgments or evaluations of that unit'sorganizational climate. Mean subscale scores for all of thenurses on the same units were calculated and used in the analysesdescribed later in this article as aggregate indicators.12
To avoid confounding our measures of these 2 organizationalcharacteristics with our measures of needlestick exposures (theoccurrence of which influenced nurses' perceptions of resourceadequacy and nurse leadership), we calculated all mean unitscores both with and without the evaluations of the nurses whohad experienced an injury. Although the results of our analyseswere the same regardless of whether the assessments of injurednurses were included in estimating these characteristics, wepresent the more conservative results (i.e., excluding the evaluationsof nurses who were injured).
Emotional exhaustion. The emotional exhaustion subscale of the Maslach Burnout Inventory14measures the extent to which nurses feel emotionally overwhelmedby their work. In the current data, this subscale had a Cronbachcoefficient of .89. In our research, we have found that thisis a psychometrically valid index that, when aggregated to the level of nursing units, gauges the extent to which working conditionsof various types have led to a generalized sense of frustration,strain, and weariness among a particular unit's nursing staff.As in the case of the organizational climate measures, we calculatedmean scores for each unit with and without data from the smallnumber of nurses who were injured. There were no differencesin the results obtained in the analyses with either approach.
Risk factors. Our survey instrument also asked nurses a series of questions about how often they recapped used needles when they cared forpatients with known and unknown HIV status (with responses rangingacross 4-point scales from "never" to "always"). A further seriesof questions asked nurses whether certain factors were presenton their units that created a significant risk of exposure tobloodborne infections, including carelessness and inexperienceof other staff and uncooperativeness of patients. Last, nurseswere asked to estimate, on a 4-point scale ranging from "notvery good" to "excellent", how good a job they thought theirhospital had done in providing them with adequate knowledgeabout AIDS and with the supplies and equipment needed to protectthemselves.
Data Analysis We first examined whether variation across hospital units in staffing and organizational climate was a significant predictorof nurses' reports of the presence of specific risk factorsassociated with needlestick injuries on their units. We thenestimated the effects of unit staffing levels and organizationalcharacteristics on the odds of nurses experiencing needlestickinjuries or near misses with a sharp over the prospective andretrospective surveillance periods. The organizational climateand staffing measures were examined both as continuous variablesand as dichotomous variables to test the possibility that nursesworking on units where conditions were poorest experienced needlesticksdisproportionately. In the analyses in which these variableswere dichotomized, nurses from the 10 units of the 40 that hadthe lowest levels of resource adequacy, nurse leadership, andnurse-to-patient ratios, and the highest levels of emotionalexhaustion, were compared with nurses from the remaining units.Because little difference was seen in the results obtained withthe dichotomous (bottom or top quartile vs all others) and continuousapproaches, and because of the ease in interpreting the oddsratios computed for dichotomized variables, only the dichotomizedresults are presented here.
Because the nurses surveyed were grouped by units, their characteristicsand their outcomes were not independent, and conventional logisticregression modeling would not have been an appropriate statisticaltechnique. Consequently, in all cases, logistic regression modelingemploying generalized estimating equations, with nursing unitas the clustering variable, was used to estimate odds ratiosand 95% confidence intervals associated with the effects ofthe different factors on them.15 In the case of the analysesof the prospective data, the number of shifts worked by eachnurse was used as a control variable because the time at riskfor injury in our analyses was directly related to the numberof shifts that nurses worked. All analyses were conducted withSAS (Version 6.12; SAS Institute Inc, Cary, NC).
RESULTS
In the retrospective portion of our study, 34 (4.3%) of the 789 nurses who responded to the questionnaires reported a needlestickinjury in the previous month. Of the 962 nurses who filled outat least 1 coupon during the prospective survey, 53 (5.5%) reportedan injury involving a needlestick or sharp containing blood,and 228 (23.7%) reported an incident involving a near miss.
Table 1 shows that nurses working on hospital units with poorerwork climates and lower staffing levels were substantially more likely to report the presence of risk factors associated with needlestick injuries. Although there is some variability in our estimates of the associations between the 4 organizationalcharacteristics and 6 risk factors, 21 of 24 of the associationswere significant, and most were substantial. Nurses on unitswith less adequate resources, lower staffing and less nurseleadership, and higher levels of emotional exhaustion were typicallytwice as likely to report the presence of risks due to staffcarelessness and inexperience, patient uncooperativeness, frequentrecapping of needles, and inadequate knowledge or supplies.
TABLE 1—Odds Ratios (ORs) and 95% Confidence Intervals (CIs) Estimating the Effects of Various Organizational Characteristics on the Odds of Nurse Reports of Different Needlestick Risk Factors on Hospital Units
Low Nurse Staffing OR (95% CI)
Low Resource Adequacy OR (95% CI)
Low Nurse Manager Leadership OR (95% CI)
High Emotional Exhaustion OR (95% CI)
Significant risk due to staff carelessness
1.92 (1.31, 2.82)
1.88 (1.25, 2.83)
1.65 (1.05, 2.58)
2.16 (1.33, 3.50)
Significant risk due to staff inexperience
1.74 (1.04, 2.92)
2.18 (1.47, 3.24)
1.80 (1.11, 2.93)
2.06 (1.31, 3.23)
Significant risk due to patient uncooperativeness
2.11 (1.32, 3.38)
2.13 (1.34, 3.40)
1.71 (1.06, 2.76)
1.32 (0.74, 2.35)
Often recaps needles used on patients with unknown HIV status
2.40 (1.29, 4.46)
3.30 (2.08, 5.23)
2.16 (1.22, 3.16)
1.78 (0.87, 3.62)
Feels hospital has not done a good job providing knowledge to protect workers
2.76 (1.72, 4.42)
2.44 (1.48, 4.00)
1.54 (0.88, 2.71)
1.94 (1.15, 3.27)
Feels hospital has not done a good job providing supplies to protect workers
3.56 (2.18, 5.81)
2.94 (1.64, 5.17)
1.86 (1.07, 3.26)
1.86 (1.02, 3.37)
Note. Odds ratios were computed with generalized estimating equations to allow for clustering by hospital unit.
Table 2 shows that these same 4 organizational characteristicsof hospital units also were related to the likelihood of incurringneedlestick injuries and reporting incidents involving nearmisses. The likelihood of experiencing needlestick injuriesin the month before our survey was 3 times higher, or nearly3 times higher, among nurses on units with less adequate resources,less nurse leadership and support, lower staffing, and higherlevels of emotional exhaustion. The likelihood of experiencingneedlesticks and near misses during the period of our prospective(shift-to-shift) data collection was similarly affected by theseadverse unit characteristics; also, odds ratios were somewhatsmaller when the prospective data were used but often involveda doubling, or near doubling, of the odds of needlesticks andnear misses. Some of these estimates were not significant atthe 95% confidence level, but virtually all were nearly so,and the importance of staffing and organization in affectingthese adverse events is indicated by the considerable consistencyin the effects estimated across the 3 separate indicators of exposure.
TABLE 2—Odds Ratios (ORs) and 95% Confidence Intervals (CIs) Estimating the Effects of Various Organizational Characteristics on the Odds of Nurses Sustaining Percutaneous Injuries and Incurring Near Misses
Retrospectively Reported Needlesticks OR (95% CI)
Prospectively Reported Needlesticks OR (95% CI)
Prospectively Reported Near Misses OR (95% CI)
Low nurse staffing
3.03 (1.22, 7.51)
2.06 (1.00, 4.25)
1.95 (1.02, 3.73)
Low resource adequacy
2.69 (1.08, 6.70)
1.73 (0.82, 3.66)
2.04 (1.08, 3.88)
Low nurse manager leadership
2.84 (1.14, 7.08)
1.56 (0.70, 3.49)
1.89 (1.06, 3.40)
High emotional exhaustion
2.54 (0.90, 7.26)
2.08 (1.03, 4.19)
1.57 (0.80, 3.10)
Note. Odds ratios were computed with generalized estimating equations to allow for clustering by hospital unit. Estimates involving prospectively reported needlesticks and near misses were computed after controlling for the number of shifts worked (time at risk).
DISCUSSION
The analyses presented here suggest that hospital nurses' exposuresto bloodborne pathogens were associated with the organizationalcharacteristics and staffing levels on the hospital units wherethey worked. Individual nurses' risks of sustaining percutaneousinjuries with used sharps were related to aggregate-level characteristicsof their hospital units such that working on units characterizedby poor working climates was associated with increased risksof injuries and near misses.
The differences in the odds ratios presented in Tables 1 and2 indicate that slightly different nursing units were designatedas having high-risk conditions when different unit characteristicswere used, and there were slight differences in our estimatesof the effects of these characteristics on the likelihood ofbeing injured. However, some of the units clearly had uniformlypoor climates, whether assessed by our survey-based measuresof organizational climate and nurse burnout or measured withinstitutional reports of nurse staffing. Nurses did not experienceneedlestick and related injuries at random. Injuries and nearmisses were clustered in specific units and were significantlymore common in units with poor working climates and less staffing.
Although needlestick injuries may be reduced by staff educationand the use of safer equipment, managers and policymakers tryingto alleviate this problem ultimately must address the effectof staffing levels and work environments on these injuries.Previous discussions of this problem have suggested that clinicalnurse specialists and nurse managers are well positioned toinfluence compliance with safer practices by teaching and modelingappropriate behavior, as well as by helping staff to betterevaluate the risks and benefits of their decisions.16 Althoughthis observation is undoubtedly accurate and provides some concreteguidelines for frontline managers and leaders, the researchreported here suggests the need to consider the broader contextof nursing care on the units and in hospitals where needlestickinjuries occur. The resource adequacy and nurse manager leadershipmeasures in this study not only are a reflection of managerialdecisions by frontline nurse leaders but also are markers ofthe extent to which the top managers in hospitals pay attentionto and invest in safe environments for staff and patients alike.
Because the hospitals and nurses in the primary study were sampledto evaluate the effect of specialized AIDS units on patientand nurse outcomes (and not to evaluate needlestick risk inhospital nurses in different settings) and because the sampleof nurses in this study was rather small, the results of theseanalyses must be interpreted cautiously. The results point toa possible effect of staffing and organization on hospital nurses'needlestick risk, but the data presented here do not permitcommentary on specific staffing levels that are potentiallysafe or unsafe or on the nature of the causal relationship involved,if there is one. We are replicating and extending these findingswith more recent and detailed data in more representative samplesof hospitals. Currently, we are examining survey data from nursesworking in a second nationwide sample of 22 hospitals in 1998.Our most recent data come from surveys completed in 1999 aspart of an ongoing international study of nursing organizationand hospital outcomes in which 43 000 nurses representing all hospitals in Pennsylvania and 3 Canadian provinces, as well as a sizable number of institutions in the United Kingdom and Germany, provided reports similar to those analyzed here.17
The recent resurgence of interest in errors and accidents inhealth care settings heralded by the Institute of Medicine's1999 report To Err Is Human18 has been characterized by dismayregarding the apparent pervasiveness of quality problems inmedical care but also by an optimism that the incidence of misadventuresin health care can be reduced by designing better systems toprevent, detect, and minimize hazards. Although needlestickinjuries are not medical errors in the strictest sense (as discussed in the Institute of Medicine's report, for instance), they are,like medical errors, adverse events that occur in medical settings,and they have been viewed by clinicians and administrators andexamined by researchers similarly. Because needlestick injuriesmay serve as a proxy for a broad range of safety and qualityissues, understanding the organizational context in which theyoccur is potentially very important. Remedying problems withunderstaffing, inadequate administrative support, and poor moralein hospitals may turn out to be among the most important steps in building a safer health care system.
Acknowledgments
This study was supported in part by grant R01-NR02280, "Outcomesof Inpatient AIDS Care," from the National Institute of NursingResearch, National Institutes of Health, and by an institutionalpostdoctoral fellowship (T32-NR07104), National Institute ofNursing Research, held by Sean P. Clarke, PhD, RN, at the Centerfor Health Outcomes and Policy Research, University of Pennsylvania.
Footnotes
S. P. Clarke planned and performed the data analysis and wrotethe article. D. M. Sloane assisted in the data analysis andcontributed to the writing of the article. L. H. Aiken was theprincipal investigator on the original study, assisted in theplanning of the analysis, and contributed to the writing ofthe article.
Peer Reviewed
Accepted for publication April 6, 2001.
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