C 2005) Journal of Clinical Psychology in Medical Settings, Vol. 12, No. 4, December 2005 ( DOI: 10.1007/s10880-005-7820-2
Pain Assessment in Pediatric Sickle Cell Disease Julie Stollger Jones,1 Steven A. Hobbs,2,3 Tara L. Brennan,2 and Jennifer Maxwell Schmidt2
The unpredictability of pain occurrence and the subjectivity of sickle cell pain create unique challenges in the assessment of pediatric sickle cell disease. A description and critique of current pain assessment measures, including verbal, motoric, and physiological-medical indices, and their applications with this population are provided. Pain assessment measures and corresponding research with pediatric sickle cell disease patients were found to be somewhat lacking, especially when compared with assessment of other pediatric problems. Major methodological concerns were revealed in that assessment has frequently relied on a single informant and pain measures often have been extended to a population beyond those on which they were normed. Findings emphasize the need for a multimodal approach to pain assessment, the use of pain ratings from multiple informants, and further development of more reliable and valid measures in order to provide adequate assessment and more effective pain management of pediatric sickle cell disease. KEY WORDS: pain assessment; pediatric pain; sickle cell disease.
Although the past decade has seen a dramatic increase in pain research, the majority of studies in this area have focused on adults rather than children. Within pediatric populations, sickle cell disease (SCD) has received limited attention in the research literature. Whereas there has been a modest amount of research addressing management of pain in these patients, the assessment of pain in pediatric sickle cell patients has received considerably less attention. Individuals with sickle cell disease produce crescent-shaped (sickle) red blood cells that have difficulty passing through small vessels and lead to occlusions in the blood stream. Such occlusions can deprive vital organs, tissue, and muscles of blood and oxygen and typically lead to vasoocclusive episodes (VOEs) that can cause severe pain (Collins, Kaslow, Doepke, Eckman, & Johnson, 1998;
Lemanek, Buckloh, Woods, & Butler, 1995). The nature of the vaso-occlusive crises can result in a vicious cycle in which the occlusion causes pain, activating the autonomic nervous system. Arousal of the autonomic nervous system produces increased muscle tension and vascular constriction, further restricting blood flow to the area of the occlusion. If this cycle can be interrupted by pharmacologic and/or nonpharmacologic interventions, blood flow may increase to areas affected by occlusion, resulting in reduction of pain (Devine, 1999). Thomas (1997) suggested that pain assessment in pediatric sickle cell disease has been notably lacking largely due to the relative absence of standardized protocols and treatment guidelines for managing pediatric sickle cell disease pain. The development of standardized pain assessment instruments is necessary to decrease the subjectivity in the assessment of pediatric SCD. Potential benefits of such efforts could be increased trust between medical staff and patients, as well as less frequent undermedication of these patients. Valid and reliable pain assessment tools are critical also in evaluating the efficacy of the pain management interventions. For example, Varni,
1 Division
of Developmental-Behavioral Pediatrics, Children’s Hospital, Greenville Hospital System, Greenville, South Carolina. 2 Department of Clinical Psychology, Georgia School of Professional Psychology at Argosy University, Atlanta, Georgia. 3 Correspondence should be addressed to Georgia School of Professional Psychology at Argosy University-Atlanta, 980 Hammond Drive, Atlanta, Georgia 30328; e-mail:
[email protected].
339 C 2005 Springer Science+Business Media, Inc. 1068-9583/05/1200-0339/0
340 Walco, and Wilcox (1990) discussed the implementation of a standardized protocol for medical staff for assessing patients with frequent reported pain episodes. The protocol decreased the subjectivity of decisions made by staff and was also thought to decrease inappropriate health care use and possible malingering behavior of patients. Many studies have examined changes in frequency and duration of hospitalization and/or emergency room visits to determine effectiveness of pain management treatment with pediatric sickle cell disease (Cozzi, Tryon, & Sedlacek, 1987; Griffen, McIntire, & Buchanan, 1994; Schechter, Berrien, & Katz, 1988; Thomas, Koshy, Patterson, Dorn, & Thomas, 1984; Trentadue, Kachoyeanos, & Lea, 1993). However, these assessments do not provide information regarding the nature of pediatric pain or changes in pain intensity. As a result, assessments of this type may not adequately measure response to intervention over the course of treatment. The purpose of the present review is to critically evaluate the general methods and specific instruments used to assess pediatric sickle cell pain as well as to examine their application in assessment and treatment studies. The pain assessment tools used with the pediatric sickle cell disease population are divided into the same three categories as general pediatric pain assessment instruments: motoric, verbal, and physiological-medical measures. Motoric measures involve the recording of the occurrence of pain behaviors by trained observers. Motor behaviors indicative of pain are difficult to observe and operationalize over the course of the VOE due to the unpredictable nature of sickle cell pain and to the phenomenon of habituation with chronic, recurrent pain. As a result, a single motoric measure (used in combination with a verbal pain measure) has been reported in the literature. In contrast, verbal measures of pain have been relied on in the vast majority of pediatric SCD studies. Verbal pain measures include various self-report methods such as interviews, rating scales, pain questionnaires, diaries, and graphic assessment approaches, that are completed by patients, parents, significant others, and medical personnel. Physiological-medical indices, rarely reported in the literature, include somatic measures commonly associated with pain such as heart rate, blood pressure, respiration rate, palmar sweating, cortisol and cortisone levels, transcutaneous oxygen pressure levels, vagal tone, endorphin concentrations, and skin resistance. This category has been expanded in the present review to include measures assessing factors
Jones, Hobbs, Brennan, and Schmidt such as emergency room use, length and duration of hospital stays, and administration of pain medication. DESCRIPTION OF PAIN ASSESSMENT MEASURES Motoric Children’s Hospital of Eastern Ontario Pain Scale The Children’s Hospital of Eastern Ontario Pain Scale (CHEOPS; McGrath et al., 1985) was developed to measure postoperative pain. The scale measures six operationally defined behaviors (crying, facial expression, verbal expression, torso position, touch behavior, and leg position). The CHEOPS was normed on 30 males (1–7 years of age) 1 hr after undergoing circumcision. Although nurses’ pain ratings correlated with the CHEOPS scores, nurses were aware of the type of surgery and when it occurred. Thus, the validity and reliability of the CHEOPS are largely in question. Verbal Affective Five Face Interval Pain Scale The Affective Five Face Interval Pain Scale (Wong & Baker, 1988) depicts line-drawn faces with a variety of differing emotional states ranging from a broad smile depicting “no pain (hurt)” to a crying, frowning face depicting “as much hurt as you can imagine.” The Affective Five Face Interval Pain Scale (FACES) was developed to assess procedural pain and normed on children under the age of 10 who were undergoing bone-marrow aspirations. The children’s reports significantly correlated with observers’ recordings of behavioral manifestations of procedural pain and observers’ ratings of procedural pain on the same Likert scale. Central Middlesex Hospital Children’s Health Diary The Central Middlesex Hospital Children’s Health Diary (CMHCHD) is a diary with a semistructured format that assesses daily well-being, frequent symptoms, pain events, coping strategies, and the impact of any pain/illness events (Gill, Shand, Fuggle, Dugan, & Davies, 1997). The diary consists of ratings of the quality of the day and general health, with children completing a 25-item symptom checklist that assesses severity of physical and psychological symptoms (e.g., stomachache, worrying) using a
Sickle Cell Pain Assessment 100-mm line. A more detailed section includes the frequency recording of all pain events including the intensity, duration, location, and perceived etiology of the pain. The methods of coping with pain and illness and the impact on nine everyday activities are also recorded. A daily pain score can be calculated by multiplying intensity and duration scores, and a mean pain score also can be determined. Structured Pain Interview The Structured Pain Interview (SPI; Gil, Williams, Thompson, & Kinney, 1991) is a minor modification of the pain interview used with adults with SCD (Gil, Abrams, Phillips, & Keefe, 1989). The interview was designed to assess pain status, activity pattern, and health care utilization. Parents are required to estimate the frequency, duration, and intensity of their child’s painful episodes on a scale of 0 (no pain) to 10 (pain as bad as it can be). Parents also estimate an hourly percentage of the child’s “uptime” (walking, sitting) versus “down time” (reclining), and percentage of time per day that the child displays a reduction in activities (school, social) during painful episodes. The SPI demonstrated adequate reliability in gathering pain, health care use, and activity reduction in adolescents with SCD (Gil et al., 1991). However, the reliability data gathered by Gil et al. focused only on adolescents, not on younger children who comprised the majority of their sample. Varni/Thompson Pediatric Pain Questionnaire Modeled after the well-known McGill Pain Questionnaire (Melzack, 1975), the Varni-Thompson Pediatric Pain Questionnaire (PPQ) is one of the few instruments developed to measure chronic and recurrent pain. Whereas many pain assessment measures have been developed to measure acute, procedural pain (which is easier to assess due to the finite period of the occurrence, duration, and predictability of the pain), the PPQ was developed to measure acute, chronic, and recurrent pain in children with Juvenile Rheumatoid Arthritis (JRA). The child form of the PPQ addresses evaluative and affective components of pain (using a list of pain descriptors) as well as pain intensity and location (using a body outline of pain sites, identification of five categories of pain, and a visual analog scale). The visual analog scale (VAS) requires the individual to place a vertical line through a 10-cm horizontal line to represent the intensity of pain along a continuum from no pain to severe pain.
341 The parent form assesses similar dimensions as well as a family health history and socioenvironmental factors that may influence the child’s pain. In addition, a VAS for use by medical staff is included (Thompson & Varni, 1986). The PPQ has been demonstrated to be a valid and reliable measure of children’s self-reports of rheumatoid disease pain and of parent and staff ratings of pain when assessing pain from rheumatoid disease (Gragg et al., 1996; Varni & Thompson, 1985, Varni, Thompson, & Hanson, 1987). Although it is a single instrument, this measure allows for multiple informants, thus providing multiple verbal measures. Adolescent Pediatric Pain Tool The Adolescent Pediatric Pain Tool (APPT) (Savedra, Holzemer, Tesler, & Wilke, 1993) was designed to measure three dimensions of postoperative pain: location, intensity, and quality. It contains front and back body outlines, a 10-cm word-graphic rating scale to indicate intensity, and a pain descriptor list grouped in three sections: sensory, affective, and evaluative qualities of pain. An estimate of the pervasiveness of the pain is determined by the number of body areas marked. The quality of pain is assessed by totaling the number of words indicated on the descriptor list (Beyer, 2000; Savedra et al., 1993). Convergent validity was noted following ratings of the 958 multiethnic children, ages 8–17 years, using four other different pain tools. Although the APPT appears to be useful across various ethnic groups, it has only been utilized once in combination with the African American Oucher Pain Scale to measure pediatric sickle cell pain (Villarruel & Denyes, 1991). Oucher Pain Scale The Oucher Pain Scale (Beyer, 1984) is a selfreport measure that was designed to assess pain intensity in children ages 3–12 years. The Oucher includes six photographs of a Caucasian preschooler displaying increasing levels of discomfort, indexed to 0, 20, 40, 60, 80, and 100 points on a numerical scale. Older children who can count to 100 may either select a number or a picture to express their level of pain intensity. The Oucher was normed on children who were experiencing postoperative pain from a variety of procedures and has demonstrated adequate reliability and validity in measuring postoperative pain in pediatric populations (Beyer & Aradine, 1986, 1988). However, its use with younger children is limited, as children under 5 years of age cannot discriminate between more
342 than three faces and do not appear to understand the value of the numerical scale (McGrath, 1995). African American Oucher Pain Scale The African American Oucher Pain Scale (Villarruel & Denyes, 1991) is a pain intensity tool presented in a poster format and has been used with children as young as 3 years of age. The African American version of the Oucher is identical to the instrument designed by Beyer (1984) but depicts pictures of a postoperative African American child instead of the Caucasian child. Physiological-Medical Indices Several studies have used objective physiologicalmedical indices to infer the presence and intensity of pain (e.g., oxygen saturation levels). Other physiological-medical indices used to infer pain frequency or intensity include the amount of pain medication administered or healthcare use measures, such as the number of emergency room visits or the number and length of hospitalizations. Measures in the motoric and/or physiologicalmedical categories often have been combined with verbal indices in pain assessment with pediatric sickle cell disease (in a manner described in the section to follow). The following sections describe the manner in which investigators have applied motoric, verbal, and physiological-medical pain measures, either individually or in combination, in studies examining pediatric sickle cell disease. STUDIES USING A SINGLE VERBAL MEASURE Numerous investigations of pediatric SCD have used a verbal measure as the sole index of pain. Sporrer, Jackson, Agner, Laver, and Abboud (1994) utilized the FACES (Wong & Baker, 1988) in an attempt to characterize pain reporting among 17 children with SCD experiencing painful VOEs. Medication dosing and schedule was based upon the patient’s report of pain on this instrument. Patients, ranging in age from 3 to 18 years, were each asked to rate their pain according to the pain scale. Results indicated that younger children (ages 3–12) reported less severe pain than did older children (ages 13–18), and that those who reported more severe pain had longer hospitalizations. The authors concluded that children’s selfreport of pain can serve as a reliable basis for medication protocols and be used to help predict length
Jones, Hobbs, Brennan, and Schmidt of hospitalization. However, as children under age 5 typically do not discriminate among more than three levels of pain (McGrath, 1995), this conclusion may be questioned in relation to younger children. Another limitation of the Affective Five Face Interval Pain Scale is that it measures only the intensity of pain. It does not assess other factors that may interfere with accurate reporting and increased perception and increased report of pain (McGrath, 1996). These factors may include emotional states such as anxiety and depression and variables such as family encouragement for the child to “be strong.” In addition, younger children who are afraid of analgesic administration may underreport their pain levels. Further, use of a smiling face rather than a neutral face to depict “no pain” can result in parents and children reporting higher levels of pain (Chambers, Giesbrecht, Craig, Bennett, & Huntsman, 1999). The advantages of using the FACES in this study appear to be the ease and timeliness of its administration and its emphasis on child-report data. The CMHCHD (Gill et al., 1997) is an instrument developed specifically on a sample of 25 children and adolescents with SCD. Patients with SCD and a group of 25 nonaffected matched controls (ranging in age from 6 to 16) and their parents completed these diaries for 4 weeks. Prior to diary keeping, participants and their parents were interviewed regarding general health and pain frequency ratings. Initial parent and child interview ratings of pain frequency were not associated with quality of life measures and did not discriminate between the clinical and nonclinical groups. However, diary measures of pain for children with SCD were generally higher than the matched controls, as the sickle cell group displayed more severe pain events and twice as much overall pain. It was inferred that the total pain score obtained from the CMHCHD was a more accurate predictor of the impact of pain on participants’ everyday life than were interviews of parent and child. STUDIES USING MULTIPLE VERBAL MEASURES Walco and Dampier (1990) used the PPQ (Thompson & Varni, 1986) to assess pain intensity and location with inpatient and outpatient sickle cell patients through a visual analog scale (VAS), Likert ratings, pain descriptors, color codings, and body outline of pain sites. Only the child self-report measures from the PPQ were used with 17 inpatient participants, ages 12–25 years, who were hospitalized for a VOE. This study demonstrated adequate clinical utility of
Sickle Cell Pain Assessment some PPQ measures. Children with sickle cell disease chose similar colors as children with other diseases to represent their levels of pain or discomfort. Adequate construct validity of the VAS was established, as physician ratings of disease severity and VAS pain ratings were highly correlated. Furthermore, VAS scores decreased over the course of the VOE, and physician dosing of analgesics corresponded fairly well with VAS scores. In this study, a limitation of the use of the PPQ with inpatient participants was the sole reliance on self-report measures, particularly for younger children. Disadvantages of the sole use of self-report measures include children’s general lack of sophisticated language to describe the pain, their fear of how pain medication will be administered, and cultural and environmental factors that may influence such reports. Walco and Dampier’s (1990) outpatient study was conducted with 35 participants between the ages of 5 and 15 years and their families and physicians, all of whom completed the full PPQ. Although the physician and parent ratings of the child’s pain were in agreement, the children’s pain descriptors revealed that parents and physicians are not fully aware of aspects of the children’s pain experience. Thus, parent or medical staff reports may not be valid when measuring pain intensity of pediatric sickle cell disease patients. Given parents’ and physicians’ inability to fully assess the child’s pain experience, the lack of physiological markers of a VOE, and the unpredictable nature of pain in sickle cell disease, it is necessary to rely heavily, but not exclusively, on children’s self-report of pain whenever possible (McAlpine & McGrath, 1999). In an attempt to replicate Walco and Damplier (1990), Graumlich et al. (2001) utilized the Parent and Child Pain Interview Questionnaires, measures that included the PPQ and structured interview items assessing parent and child knowledge of sickle cell disease and strategies used to cope with pain. Additional measures were used to collect demographic information, beliefs about health and illness, and perceptions of the disease and associated pain. Participants included 25 children with a mean age of 10 years and their primary caregivers. Reports of pain intensity and qualitative pain descriptors were similar for both parents and children. However, children tended to report physical aspects of pain, whereas parents focused on cognitive and emotional factors related to pain. This demonstrates the importance of gathering data across informants in order to gain a more complete picture of the child’s pain experience. Although the PPQ appears to be the most complete of all the instruments used to measure pain in pediatric sickle cell disease, it
343 has been used infrequently with this population and only in relatively small samples. In addition, the entire tool has been used only with outpatients, as administration of the full PPQ may not be practical in some settings due its length. Beyer (2000) utilized the APPT (Savedra et al., 1993) and the African American Oucher (Villarruel & Denyes, 1991) to examine the effectiveness of analgesia with inpatients experiencing VOEs. The type, dose, and frequency of analgesics given, and the child self-reported pain intensity (e.g., African American Oucher and APPT) were used to determine the effectiveness of analgesia for 21 participants, ages 6– 16 years. Pain measures were completed prior to and following the administration of analgesia. Results indicated that 15 of the 21 participants continued to experience moderate to severe pain by the end of the 2-hr interview that followed administration of analgesia. This further indicated that sickle cell disease pain may require continuous adjustment of pain management interventions. Beyer (2000) found that scores from the APPT and African American Oucher were highly correlated and demonstrated convergent validity. Although the African American Oucher is more culturally sensitive for African American children (Conner-Warren, 1996), this measure was not normed on children experiencing sickle cell pain or on children under age 8. An additional limitation is that neither the African American Oucher nor the APPT adequately consider factors that may exacerbate the experience of pain. Conner-Warren (1996) used the African American Oucher and pain diaries to assess pain intensity during VOEs and the effects of home management methods. In this study, diaries were collected from 30 children ranging from 4 to 18 years of age. The pain scores were to be recorded at the onset of the first VOE occurring at home. The patients were also instructed to check the pain management technique(s) utilized and list any additional techniques that they found helpful. Although the African American Oucher has been demonstrated to be an ethnically sensitive tool, it has disadvantages similar to those of other instruments in its use of a six-point Likert scale and diaries that may be too complex for younger children. STUDIES USING COMBINATIONS OF MEASURES Some studies have used a combination of the three categories of measures, such as verbal and motoric indices or verbal and physiological-medical
344 indices, in an attempt to increase reliability of measurement. Verbal and Motoric Measures Jacobson, Kopecky, Joshi, and Babul (1997) utilized the Oucher and the CHEOPS to compare the efficacy of oral controlled released morphine with continuous intravenous morphine in 56 children experiencing severe VOEs. Patients ranging in age from 5–17 years were given an initial dose of intravenous morphine and were then randomized into two groups, those receiving oral morphine and intravenous placebo versus those receiving an oral placebo and intravenous morphine. Pain was assessed at four predetermined times each day with the Oucher and the CHEOPS. Mean overall pain scores were similar in both groups and the pain scores from all scales were adequately correlated. Although this study did not use pain assessment tools to determine dosing or type of medication given, patient and observer pain ratings largely determined the efficacy of oral morphine. Limitations of this study include the selection of measures not used previously with pediatric sickle cell patients and less culturally sensitive than other instruments (Conner-Warren, 1996). Verbal and Physiological-Medical Indices Isolated studies have used physiological-medical indices as sole measures of pain assessment (Griffen, McIntire, & Buchanan, 1994; Thomas et al., 1984). Cozzi et al. (1987) investigated the effectiveness of electromyography and thermal biofeedback for reducing pain through a review of pain diaries as well as changes in muscle tension and body temperature. Eight patients ranging from 10 to 20 years of age kept a daily record of their level of pain based on a 5-point Likert scale. Patients displayed statistically significant reductions in pain medication taken, reported pain intensity, and state anxiety. However, no change in emergency room visits or inpatient hospitalizations were noted. Whereas some studies use a decrease in frequency and/or duration of hospital/emergency room visits as an index of treatment effectiveness, Hardwick, Givens, Monroe, King, and Lawley (1999) included a VAS to investigate the effect of ketorolac for pediatric sickle cell vaso-occlusive pain crises. The 29 participants, ranging in age from 5 to 18 years, presented to a pediatric emergency department with a total of 41 distinct VOEs. Participants were then
Jones, Hobbs, Brennan, and Schmidt randomized into two groups (one receiving ketorolac or one receiving a placebo). Participants reported their pain levels using the VAS prior to receiving an initial dose of morphine and IV fluids. Pain intensity was measured hourly throughout the 6-hr observation, and patients in both groups were administered further doses of morphine every 2 hr based upon their reported pain levels. Ketorolac did not demonstrate a synergistic analgesic effect, as no differences were observed in total dose of morphine received, rate of hospital admissions, or return visits to the emergency department. No significant differences were noted in the reduction of pain on the VAS between participants receiving ketorolac and those receiving a placebo. Although a measure such as the VAS to determine the need to deliver pain medication may be helpful, the inherent difficulties in relying solely on self-report measures and/or a single measure of pain have been noted. Yaster, Tobin, Billett, Casella, and Dover (1994) utilized oxygen saturation levels and a VAS to examine the efficacy of epidural analgesia for decreasing VOE pain in nine children, ages 3 to 16, who had not responded to conventional analgesic therapy. The study included pain ratings on a 10-point VAS, arterial oxygen saturation levels, and plasma lidocaine levels. Although a few participants also required the use of a fentanyl patch to further decrease pain, epidural analgesic was reportedly quite effective in decreasing pain. Initial pain ratings of 8–10 changed to 0–2 almost immediately following the epidural, and oxygen saturation levels increased significantly. Although oxygen saturation level is not an adequate indicator of pain intensity, it is often used as an aid in the assessment of pain. Although such measures should not be used as the sole measure in pain assessment, the inclusion of the VAS addressed the need for additional pain indices and appeared to be appropriate for the age of participants in this study. In a retrospective study, Trentadue et al. (1993) compared two regimens of patient controlled analgesia (PCA) in terms of safety, efficacy, and cost of treatment. They reviewed the medical charts of 26 children with sickle cell disease who were collectively hospitalized 60 times. Although the specific assessment procedures were not indicated, the authors indicated that children with high-dose PCA/low basal infusion reported lower pain scores on Day 2 of hospitalization, used significantly less morphine, and spent fewer days in the hospital when compared to the group receiving low-dose PCA/high basal infusion. The appropriateness of the assessment tool used to document pain in the medical chart could not be determined, as
Sickle Cell Pain Assessment the authors provided no information on the specific instrument. The SPI was employed by Gil et al. (1993) in their examination of 9-month follow-up data from a longitudinal study of children and adolescents with SCD and their parents. At the outset of the study, the 70 children and adolescents, ranging in age from 7 to 18 years, completed the Coping Strategies Questionnaire (CSQ) (Rosenstiel & Keefe, 1983) identifying three dimensions of coping: Negative Thinking, Passive Adherence, and Coping Attempts. Disease severity was obtained from parent report and medical records. At follow-up, the children and adolescents repeated the CSQ and parents completed the SPI, answering questions based upon the previous 9 months. The number of ER visits, hospitalizations, and phone calls/visits to physicians were also obtained from the parent. Results indicated that Coping Attempts were associated with higher levels of activity (e.g., participation in school and social activities) during painful episodes. Passive Adherence and increases in Negative Thinking were associated with more frequent health care contacts during the 9-month period. Adequate reliability and validity has been demonstrated for the SPI with children and adolescents with SCD, as well as satisfactory convergence between adolescents and parents reports of pain intensity. However, as no pain intensity ratings were obtained from younger children, the reliability of parental pain intensity reports for younger children on the SPI remain in question. A further limitation of the Gil et al. (1993) study includes the primary reliance on parent report in assessing outcome. Parent reports need to be validated by other measures, such as school attendance records and self-monitoring data from the child, as parent reports may be somewhat inaccurate sources for such data. DISCUSSION As can be seen from the previous description of measures and investigations, sickle cell pain assessment is often inadequate, especially when compared with assessment of other pediatric pain conditions. As noted by Simon, Lobo, and Jackson (1999), few pain assessment instruments have shown adequate reliability and validity in measuring pediatric sickle cell pain. In addition, those instruments with demonstrated efficacy have been used infrequently to determine the effectiveness of pain management interventions (Simon et al., 1999).
345 Some of the major concerns of sickle cell pain assessment studies involve small sample sizes, nonrepresentative participant samples, lack of matched control groups in intervention studies, and limited replication studies. These factors further impact the reliability, validity, and generalizability of findings. Likewise, some studies have used convenience samples, i.e., patients referred due to a significant number of painful episodes. When recruiting only patients with greater frequency or intensity of pain episodes than typical, samples and resulting measurements may not be representative of the larger population of pediatric sickle cell patients. In contrast, pain assessment studies with other pediatric conditions often have included more heterogeneous participant samples. Given the relative lack of adequate research supporting the psychometric properties of assessment measures for sickle cell pain, the outcomes of intervention trials using such measures may be questioned. Appropriate validation efforts would include comparisons of the results on a given sickle cell pain instrument with those from instruments that have adequately measured pain in other studies. Children and adolescents could also complete self-monitoring tasks to increase the validity of reports of pain intensity and interference with daily activities (Shapiro, Dinges, Orne, & Bauer, 1995). Another area of concern regarding sickle cell pain assessment is the frequent use of a single informant source when assessing the child’s pain intensity. Some studies have utilized only parent or medical staff ratings of pain (Gil et al., 1993; Robieux et al., 1992), whereas others have examined only child self-report of pain (Beyer, 2000; Conner-Warren, 1996; Hardwick et al., 1999; Schecter et al., 1988; Shapiro et al., 1995; Sporrer et al., 1994; Yaster et al., 1994). The use of data based upon parent or staff ratings of pain typically does not provide adequate information regarding the pain experience, especially given the subjective nature of sickle cell pain. If observers are unfamiliar with the child, they may not be aware of the child’s typical pain behaviors. In that instance, a decrease in observable “pain behaviors” may not necessarily indicate a decrease in pain intensity. Thus, patients, parents, medical staff, and other persons in the child’s natural environment should serve as informants regarding the patient’s pain intensity and interference with daily activities. Given the subjectivity of sickle cell pain, selfreport measures should be used whenever possible. However, it should be recognized that self-report
346 measures provide a less than adequate picture of the child’s pain for multiple reasons. Children who are preverbal or who have unsophisticated language to describe the pain obviously will have difficulty communicating aspects of the pain experience. In addition, some children may under-report their pain level for fear of the administration of pain medication by injection or due to social/cultural factors expectancies to appear stronger or healthier by denying pain or refusing medication. Only one measure reviewed in this paper, the Central Middlesex Hospital Children’s Health Diary, was developed specifically for children and adolescents with sickle cell disease. Other instruments adapted for use in sickle cell pain assessment studies, including the Adolescent Pediatric Pain Tool and the Children’s Hospital of Eastern Ontario Pain Scale, have demonstrated modest reliability and validity for use with pediatric sickle cell patients (Beyer, 2000; Jacobson et al., 1997). Further, measures have been used with age ranges for which they have not been normed. For example, some instruments have been used with pediatric sickle cell disease participants who were much older than the norms provided for the instrument (Beyer, 2000) or with children who were too young to complete the required questionnaires/diaries or too young to accurately discriminate between more than three faces or 100 point VAS measures (Beyer, 2000; Conner-Warren, 1996; Gil et al., 1993; Gill et al., 1997; Hardwick et al., 1999). It appears than pain intensity may be adequately measured with outpatient populations using existing assessment tools. Although Gill et al. (1997) developed a diary specifically for pediatric sickle cell patients, their instrument focuses more on the impact of the pain and the coping strategies used to deal with the pain. While this is important information to gather, especially when developing a treatment protocol to use with more chronic, less severe pain, decreased pain intensity should be one of the primary foci with patients who are hospitalized with a VOE. Diaries can also provide information regarding the antecedents and consequences of the painful episode in a manner such as the Varni-Thompson Pediatric Pain Questionnaire. However, outpatients may be less diligent about keeping diaries due to the infrequent nature of their pain when compared with other populations who experience more frequent pain episodes. Given the nature of sickle cell pain, multimodal assessment clearly provides the most reliable and valid approach to measurement of pain in children
Jones, Hobbs, Brennan, and Schmidt and adolescents. Ideal pain assessment for sickle cell disease necessitates multiple informants due to the lack of objective measures, lack of other informants’ complete understanding of the sickle cell pain experience, and the inherent biases in self-report measures. As such, the PPQ appears to be the most complete pain assessment measure currently available for pediatric sickle cell patients. However, relatively few studies have been conducted using this instrument. When administered in its entire form, the PPQ is quite lengthy and may not be feasible for use in a busy clinic or during inpatient stays. Although inpatient children may be readily available for assessment, caregivers may not be available to complete their portion of the pain assessment, and medical staff may not be aware of the child’s typical expression of pain. Although Walco and Dampier (1990) utilized only the self-report portion of the PPQ with inpatients, thus significantly shortening the length of this instrument, exclusive reliance on self-report measures alone raises concerns. Perhaps a shorter version of the PPQ, including both self- and other-report, would have increased practicality without sacrificing reliability and validity. A shorter version also could be normed more readily on the pediatric sickle cell population to further increase the validity of its use with this population. Because adequate assessment can facilitate more effective pain management, reliable and valid pain assessment is imperative for children with sickle cell disease. Although there have been some reported improvements in the pharmacological treatment of sickle cell disease, the actual effects of these treatments may be unclear due to the lack of adequate assessment. Whether patients are provided medication or not may be largely influenced by medical staff perceptions of the child’s pain experience. Therefore, pain management (i.e., both pharmacological and nonpharmacological) for all pediatric sickle cell patients likely will not improve without the standardized use of adequate pain assessment tools. The development of such instruments could ultimately lead to more standardized treatment protocols as well. Although the PPQ has shown promising results with pediatric sickle cell patients, there currently appears to be no standard or consistent method of assessing sickle cell pain prior to and during treatment. The inherent difficulties in assessing pain notwithstanding, the findings of this review emphasize the critical need to develop psychometrically sound measures to ensure adequate and ethical treatment for this patient population.
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