Pain Assessment in Impaired Cognition

Abstract

The Pain Assessment in Impaired Cognition (PAIC-15) is an internationally developed, standardized, observational psychometric instrument specifically designed to assess pain in older adults and adults living with significant cognitive impairment, such as dementia. Developed under the auspices of the European Cooperation in Science and Technology (EU COST) Action TD1005 (“Pain in impaired cognition, especially dementia”), the instrument addresses the widespread clinical challenge of recognizing and managing pain in non-communicative individuals. The PAIC-15 contains 15 observable behavioral descriptors evenly divided across three distinct empirical domains: Facial Expressions (5 items), Body Movements (5 items), and Vocalizations (5 items). Each item is evaluated using a 4-point Likert-type scaling system ranging from 0 (“Not present”) to 3 (“Great degree”), with an explicit coding option (“x”) reserved for behaviors that are not assessable or cannot be observed. Summed total scores range from 0 to 45, where higher scores signify increased likelihood and severity of physical pain. Psychometric evaluations across multiple European cohorts indicate robust internal consistency (Cronbach’s α typically ranging from .75 to .89 across subscales and total score), excellent inter-rater reliability (Intraclass Correlation Coefficients [ICC] > .80 for total scores), and robust convergent validity when compared against legacy instruments such as the PAINAD, PACSLAC, and MOBID-2. Confirmatory factor analyses support a multidimensional, hierarchical three-factor model that aligns with behavioral pain communication theory. The PAIC-15 represents a crucial milestone in geriatric neuropsychology, clinical nursing, and palliative medicine, providing a validated, parsimonious, and cross-culturally robust metric for acute, procedural, and chronic pain surveillance.

Keywords

Pain Assessment in Impaired Cognition, PAIC-15, dementia, observational pain assessment, psychometrics, facial expressions, vocalizations, body movements, cognitive impairment, geriatric neuropsychology, behavioral pain scale, palliative care, COST Action TD1005

Authors

The Pain Assessment in Impaired Cognition was developed through an extensive collaborative effort spearheaded by researchers within the European COST Action TD1005 (“Pain in impaired cognition, especially dementia”). The primary lead investigators and authors responsible for its conceptualization, item reduction, and empirical validation include:

• Stefan Lautenbacher, Ph.D. — Professor of Physiological Psychology, Department of Physiological Psychology, University of Bamberg, Bamberg, Germany. An authority on experimental pain research, facial displays of pain, and pain processing in neurological disorders.
• Wilco P. Achterberg, M.D., Ph.D. — Professor of Institutional Care and Elderly Care Medicine, Department of Public Health and Primary Care, Leiden University Medical Center (LUMC), Leiden, The Netherlands. A leading geriatrician focused on pain epidemiology, musculoskeletal health, and rehabilitation in dementia.
• Miriam Kunz, Ph.D. — Professor of Medical Psychology and Sociology, Department of Medical Psychology, University of Augsburg, Augsburg, Germany, and formerly of the University of Groningen. Internationally recognized for work on the objective coding of facial expressions of pain using the Facial Action Coding System (FACS).
• Astrid H. van Dalen-Kok, M.D., Ph.D. — Senior Clinical Researcher, Department of Public Health and Primary Care, Leiden University Medical Center (LUMC), Leiden, The Netherlands. Lead investigator for the prospective multi-center Dutch validation studies of the 15-item finalized scale.
• The COST Action TD1005 Consortium — A transnational collaborative network comprising clinicians, psychometricians, neuroscientists, and geriatricians across more than a dozen European countries, dedicated to harmonizing and standardizing pain assessment methodologies in neurodegenerative diseases.

Purpose

The primary clinical and scientific purpose of the PAIC-15 is to provide a reliable, objective, and clinically feasible observational tool to detect, monitor, and quantify pain in individuals whose communicative abilities are severely degraded by progressive neurocognitive decline. The assessment of pain relies fundamentally on subjective self-report, traditionally operationalized through Visual Analog Scales (VAS), Numeric Rating Scales (NRS), or Verbal Rating Scales (VRS). However, as neurodegenerative conditions such as Alzheimer’s disease, vascular dementia, frontotemporal lobar degeneration, and Lewy body dementia advance, patients inevitably experience progressive aphasia, agnosia, apraxia, and abstract conceptual reasoning deficits. These deficits strip individuals of the capacity to accurately interpret and communicate internal somatosensory states, describe noxious sensations, or map their perceived pain intensity onto traditional ordinal scales.

Consequently, individuals with moderate-to-severe cognitive impairment are at alarming risk for both under-detection and under-treatment of chronic and acute pain conditions, including osteoarthritis, neuropathies, musculoskeletal contractures, visceral discomfort, and ischemic wounds. Unrelieved pain in this vulnerable population precipitates severe behavioral and psychological symptoms of dementia (BPSD), manifesting as psychomotor agitation, verbal aggression, catastrophic physical reactions during routine hygiene care, depressive withdrawal, insomnia, and accelerated cognitive decompensation. In clinical practice, these behavioral reactions to unaddressed physical pain are frequently misinterpreted as psychiatric symptoms, inappropriately leading to the prescription of sedatives, anxiolytics, and antipsychotics that carry substantial morbidity and mortality risks.

The PAIC-15 was purposefully engineered to rectify these issues by distilling an unwieldy literature of redundant observational behavioral indicators into a refined, meta-analytically supported 15-item core instrument. The tool serves multiple interrelated functions across geriatric healthcare settings:

• Acute and Procedural Monitoring: Assessing transient spikes in nociceptive distress during dynamic physical maneuvers, such as morning transfers, dressing, wound care, and physiotherapy.
• Baseline and Resting Surveillance: Evaluating quiet somatic comfort, postural relaxation, and subtle manifestations of persistent somatic or visceral pain while patients are sedentary.
• Pharmacological Titration: Providing objective, standardized pre- and post-intervention outcome metrics to determine the efficacy and tolerability of analgesic regimens (e.g., acetaminophen, transdermal buprenorphine, gabapentinoids).
• Cross-National Clinical Research: Standardizing pain measurement in international randomized controlled trials and epidemiological investigations, eliminating the psychometric variance associated with regional legacy instruments.

Psychological Construct

The psychological construct assessed by the PAIC-15 is inferred pain state, operationalized through systematic observation of behavioral indicators across three expressive domains: Facial Expressions, Body Movements, and Vocalizations. Pain is inherently a multi-system sensory, affective, and cognitive phenomenon. When cortical and communicative pathways are compromised, the affective and motivational components of the pain matrix involuntarily trigger evolutionary nonverbal motor patterns. The PAIC-15 categorizes these nonverbal signs into three distinct behavioral dimensions:

1. Facial Expressions (Items 1–5)

The human face is the most phylogenetically conserved, sensitive, and immediate communicative channel for conveying acute affective and sensory distress. Drawing from rigorous biometric investigations using Paul Ekman’s Facial Action Coding System (FACS), the PAIC-15 identifies five prototypical facial action patterns reliably associated with nociceptive input across cognitively intact and impaired populations:

• Frowning: Activation of the corrugator supercilii and depressor supercilii muscles (FACS Action Unit [AU] 4), drawing the eyebrows together and downward, creating vertical skin furrows between the brows. This movement reflects primary distress and sensory displeasure.
• Narrowing eyes: Contraction of the orbital portions of the orbicularis oculi muscle (FACS AU 6 and AU 7), causing tightening of the eyelids, elevation of the cheeks, and narrowing of the palpebral fissure. This protective ocular reaction commonly accompanies sharp or escalating sensory discomfort.
• Raising upper lip: Contraction of the levator labii superioris (FACS AU 9 and AU 10), elevating the upper lip, frequently exposing the upper teeth and deepening the nasolabial fold. This action is strongly linked to the affective and aversive processing of pain.
• Opening mouth: Dropping of the mandible via relaxation of the masseter and contraction of the pterygoid and digastric muscles (FACS AU 25, 26, or 27), presenting as an agape jaw reflecting severe physical shock, distress, or breath-holding patterns during pain surges.
• Looking tight: A globalized, sustained isometric tension across the mimetic musculature of the face, manifesting as a rigid, strained, or stony visage lacking natural affective fluidity, signaling continuous, tonic somatic strain.

2. Body Movements (Items 6–10)

This subscale evaluates macroscopic gross and fine motor behaviors reflecting escape impulses, autonomic distress, and somatic defense mechanisms:

• Resisting care: Active physical opposition against healthcare personnel during assistance with activities of daily living (ADLs), such as pushing hands away, clenching limbs, or pulling back during dressing, bathing, or repositioning. In dementia, this behavior is often driven by pain evoked by movement.
• Guarding: Involuntary or deliberate posturing, bracing, or protective positioning of a specific limb, joint, or body sector. Guarding acts to shield a sensitized or injured anatomical region from external pressure or kinetic movement.
• Rubbing: Repetitive massaging, clasping, stroking, or clutching of an anatomical area, representing a tactile self-soothing reflex that engages peripheral large-diameter sensory fibers to suppress smaller nociceptive fibers.
• Restlessness: Generalized, purposeless, or agitated motor activity, such as shifting in chairs, continuous tossing and turning in bed, pacing, or uncoordinated limb movements driven by acute internal somatic dysesthesias.
• Freezing: Sudden behavioral arrest, motor inhibition, or catalepsy-like rigidity when an individual anticipates or experiences a painful sensation, effectively locking movement to minimize further joint or tissue stress.

3. Vocalizations (Items 11–15)

Acoustic signaling serves as an auditory distress signal directed at the environment, conveying immediate threats to organismic integrity:

• Groaning: Low-pitched, guttural, sustained, non-melodic acoustic emissions, often synchronized with exhalation, conveying dull, heavy, or persistent visceral/musculoskeletal pain.
• Screaming: High-pitched, loud, sharp, unconstrained vocal blasts indicating sudden, piercing, or acute mechanical pain.
• Pain-related words: Verbatim or fragmentary utterances of explicit linguistic signifiers of pain (“Ouch,” “It hurts,” “Stop, my hip,” “Burning”), even when full, conversational self-report cannot be sustained.
• Calling out: Repetitive verbal invocations, demands, or cries for attention or rescue (“Help me,” “God help,” “Nurse, please”) fueled by distressing sensory input and associated panic.
• Mumbling: Low-amplitude, indistinct, continuous grumbling or perseverative phonation expressing low-grade, persistent somatic misery or discomfort.

Theoretical Framework

The construction of the PAIC-15 is grounded in Kenneth Craig’s Social Communication Model of Pain (Craig, 2002; Prkachin, 1992), alongside modern neurobiological theories of pain processing in neurodegenerative diseases. Craig’s model posits that pain is not merely an isolated, private intrapersonal sensation, but an active, interpersonal communicative process comprised of distinct stages: internal neurobiological registration, spontaneous or controlled encoding into nonverbal and verbal expressive behaviors, transmission across the social environment, and decoding/interpretation by observers.

In cognitively intact individuals, higher-order cortical networks (including the dorsolateral prefrontal cortex, orbitofrontal cortex, and language networks) exert inhibitory, regulatory control over primitive expressive outputs. This allows intact adults to modulate their outward behavior and convey their experiences through symbolic, nuanced language. In progressive dementia, however, significant cortical atrophy, neurofibrillary tangle pathology, and amyloid plaques preferentially disrupt lateral pain pathways (which encode sensory-discriminative properties such as location and intensity) and language centers, while relatively sparing or disinhibiting medial pain pathways (comprising the anterior cingulate cortex, insular cortex, amygdala, and brainstem centers).

This neuroanatomical dissociation generates a unique clinical phenomenon: patients experience profound emotional, motivational, and sensory distress from pain, but their capacity to self-regulate, contextualize, and verbally communicate this distress is lost. Instead, pain manifests directly via phylogenetically older, primitive motor circuits that express affective distress through involuntary facial configurations (mediated by the facial nucleus and brainstem-limbic loops), protective postural reflexes, and primitive acoustic alarms. The PAIC-15 operationalizes this theoretical paradigm by systematically decoding these primitive expressive outputs into an objective, standardized metric.

Furthermore, the PAIC-15 was built upon the empirical foundation of the Facial Action Coding System (FACS). Prior research by Kunz, Lautenbacher, and colleagues demonstrated that facial displays of pain remain intact and are often amplified in individuals with Alzheimer’s disease due to the loss of top-down inhibitory frontal regulation. By selecting facial items that map directly onto empirical FACS Action Units, the PAIC-15 integrates robust biomechanical measurement into clinical bedside practice.

Validity

The PAIC-15 has undergone extensive international validation to establish its psychometric properties across diverse clinical populations, including nursing home residents, acute geriatric ward patients, and specialized psychogeriatric units.

Content and Face Validity

The content validity of the PAIC-15 is uniquely robust due to its origins within the European COST Action TD1005. The scale was not generated de novo by a single research team; rather, it was developed through a rigorous multi-stage consensus procedure. An exhaustive inventory of all items from every existing observational pain tool worldwide (e.g., PACSLAC, DOLOPLUS-2, Abbey Pain Scale, MOBID-2, PAINAD) was compiled. Over multiple international Delphi rounds and item-selection studies involving hundreds of European pain experts, clinicians, and researchers, items were systematically evaluated for their clinical feasibility, conceptual distinctiveness, and psychometric sensitivity. This process eliminated ambiguous items (e.g., changes in appetite, vital sign fluctuations) and preserved the 15 most robust, unambiguous behavioral markers of pain.

Construct and Known-Groups Validity

Construct validity has been repeatedly demonstrated via experimental and observational known-groups paradigms. In validation cohorts (e.g., van Dalen-Kok et al., 2018; Lautenbacher et al., 2016), researchers compared PAIC-15 scores across systematically differentiated behavioral states:

• Rest vs. Movement: In individuals with painful conditions (such as advanced hip osteoarthritis or localized trauma), PAIC-15 total and subscale scores increased significantly during mobilization, physical therapy, or transfer procedures compared to baseline resting states (typically moving from mean scores of 1.2–2.4 at rest to 6.8–12.5 during movement, p < .001).
• Pain vs. Pain-Free Groups: Patients with verified somatic pathologies consistently scored significantly higher on the PAIC-15 than matched patients without painful diagnoses (Cohen’s d ranging from 0.82 to 1.34, representing large to very large effect sizes).

Convergent Validity

Convergent validity has been established by evaluating the degree of statistical correspondence between the PAIC-15 and other validated observational instruments:

• Correlations with the Pain Assessment in Advanced Dementia (PAINAD) scale consistently range between r = .72 and .84 (p < .001).
• Correlations with the Pain Assessment Checklist for Seniors with Severe Dementia (PACSLAC) and PACSLAC-II show strong alignment, ranging between r = .68 and .81.
• Correlations with the Mobilization-Observation-Behavior-Intensity-Dementia-2 (MOBID-2) instrument during active movement conditions range between r = .70 and .79.
• In individuals with mild-to-moderate cognitive deficits who retain limited capacity for self-report, PAIC-15 scores correlate moderately with Numeric Rating Scale (NRS) pain scores (r = .45 to .62, p < .01), which conforms to theoretical expectations given that observational behavior reflects affective distress alongside pure sensory intensity.

Discriminant and Criterion Validity

Discriminant validity is supported by data demonstrating that the PAIC-15 does not unduly reflect non-pain-related neuropsychiatric disturbances. Although motor restlessness may appear in generalized anxiety, the composite score of the PAIC-15 differentiates acute pain from baseline neuropsychiatric apathy and depression (correlations with Neuropsychiatric Inventory [NPI] non-pain subscales remaining low, r < .25). Criterion-related predictive validity has been verified through double-blind and prospective open-label analgesic trials: administration of standardized analgesic therapy yields statistically significant decreases in PAIC-15 scores (mean reductions of 40% to 65% post-intervention), confirming the instrument’s sensitivity to therapeutic change.

Reliability

The PAIC-15 exhibits solid psychometric reliability across internal consistency, inter-rater, and intra-rater dimensions in clinical and experimental evaluations.

Internal Consistency

Internal consistency metrics for the full 15-item scale and its three distinct domains have yielded strong coefficients across multiple independent European cohorts:

• Total Scale: Cronbach’s α coefficients consistently range between .82 and .89 across heterogeneous nursing home cohorts, indicating a cohesive yet non-redundant set of behavioral items. McDonald’s ω values closely mirror these results (.84 to .90).
• Facial Expressions Subscale: Cronbach’s α ranges from .74 to .82.
• Body Movements Subscale: Cronbach’s α ranges from .68 to .76.
• Vocalizations Subscale: Cronbach’s α ranges from .75 to .83.

Inter-Rater Reliability

Given that the PAIC-15 relies on bedside observation, inter-rater agreement is critical. Standardized testing involving paired evaluations (e.g., registered nurses, nursing assistants, and trained research psychologists) observing the same mobilization or care episodes has demonstrated high inter-observer concordances:

• Total Score: Intraclass Correlation Coefficients (ICC, two-way random model, absolute agreement) range between .81 and .93, reflecting excellent inter-rater stability.
• Item-Level Agreement: Unweighted and quadratic weighted Cohen’s κ and Fleiss’ κ coefficients across individual items range from .55 to .84. The highest item agreement is observed for objective facial features (Frowning, Narrowing eyes) and overt vocal features (Screaming, Groaning), whereas subtle motor items (Looking tight, Freezing) fall into the moderate-to-good agreement category (κ ≈ .58–.68).

Test-Retest and Intra-Rater Reliability

In stable clinical conditions without physical manipulation or changes in analgesic therapy, test-retest reliability across 1- to 4-hour observation windows yields ICCs of .78 to .86. Intra-rater reliability assessed via blinded video-recorded clinical encounters reveals high scoring stability (ICC > .88).

Factor Analysis

The dimensional structure of the PAIC-15 has been evaluated using both Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) across diverse pan-European geriatric datasets.

Exploratory Factor Analysis (EFA)

During the developmental phase of COST Action TD1005, EFA with oblique rotation (Promax and Oblimin) consistently extracted three primary factors corresponding to observable behavioral channels: Facial Expressions, Body Movements, and Vocalizations. These three components accounted for approximately 52% to 64% of the total variance across clinical samples. Cross-loadings between items were low (< .30), demonstrating clear empirical separation between the observational domains.

Confirmatory Factor Analysis (CFA)

Subsequent psychometric investigations (e.g., van Dalen-Kok et al., 2018; Lautenbacher et al., 2016) subjected candidate models to rigorous CFA testing. A hypothesized three-factor correlated model demonstrated superior fit compared to single-factor (unidimensional) or two-factor models:

• Model Fit Indices:
  • Comparative Fit Index (CFI) = .94 to .97 (surpassing the standard ≥ .90 benchmark).
  • Tucker-Lewis Index (TLI) = .93 to .96.
  • Root Mean Square Error of Approximation (RMSEA) = .042 to .058 (with 90% confidence intervals well below the .08 threshold).
  • Standardized Root Mean Square Residual (SRMR) = .045 to .052.
• Standardized Factor Loadings:
  • Facial Expressions: Loadings range from .62 to .86 (with Frowning and Narrowing eyes consistently exhibiting the highest factor saturation, λ > .80).
  • Body Movements: Loadings range from .54 to .78 (with Guarding and Resisting care yielding λ > .72).
  • Vocalizations: Loadings range from .61 to .84 (with Groaning and Pain-related words exhibiting λ > .78).

Furthermore, higher-order hierarchical CFA models confirming a single secondary “Global Pain Expression” factor governing the three first-order factors showed comparable goodness-of-fit indices, supporting the clinical practice of summing all 15 items into a single unified score.

Instrument / Measurement Tool

The PAIC-15 is structured as follows:

• Test Type: Direct observational behavioral rating instrument.
• Target Population: Older adults and adults with mild, moderate, or severe cognitive impairment (such as dementia, traumatic brain injury, intellectual disabilities, or delirium) who are unable to communicate reliable verbal self-reports of pain.
• Administration Format: Standardized bedside observation conducted by trained healthcare professionals (e.g., registered nurses, geriatricians, physical therapists, clinical psychologists) during rest or dynamic care interactions.
• Item Count: 15 items distributed equally across three subscales:
  • Facial Expressions: 5 items (Items 1–5)
  • Body Movements: 5 items (Items 6–10)
  • Vocalizations: 5 items (Items 11–15)
• Observation Window: Typically 3 to 5 minutes during standardized dynamic care (e.g., transfers, personal hygiene, passive or active limb mobilization) or at rest.
• Response Scale: 4-point rating scale:
  • 0 = Not present (the behavior did not occur during the observation period)
  • 1 = Slight degree (the behavior was observed briefly, subtly, or in a minor form)
  • 2 = Moderate degree (the behavior was observed clearly, with definite intensity or repeated occurrences)
  • 3 = Great degree (the behavior was observed with pronounced, continuous, or extreme intensity)
  • x = Not assessable / Not observed (used when an item cannot be evaluated, e.g., the patient’s face is obscured, or the patient is paralyzed)
• Scoring and Interpretation:
  • Subscale scores are calculated by summing valid item ratings within each category (each domain ranging from 0 to 15).
  • The Total Score is computed by summing all 15 items, yielding a range from 0 to 45.
  • Higher scores indicate a higher probability and severity of pain.
  • Handling Missing / Non-Assessable Data: If more than 3 items are marked as “x” (Not assessable), the total score should not be computed. For 1 to 3 non-assessable items, mean imputation of the remaining subscale items can be utilized for research protocols.
  • Clinical Decision Threshold: While continuous tracking is recommended, empirical studies suggest that a total score of ≥ 3 to 4 points during movement strongly warrants targeted clinical evaluation, non-pharmacological adjustment, or trial analgesic titration.

Permissions & Fee and Test Year

The conceptual framework and developmental item pools of the PAIC-15 were established between 2011 and 2015 under the European COST Action TD1005 (“Pain in impaired cognition, especially dementia”). The finalized 15-item instrument was systematically validated and published between 2016 and 2018 (e.g., Lautenbacher et al., 2016; van Dalen-Kok et al., 2018).

The PAIC-15 is an open-access, free-of-charge clinical and research measurement tool. In accordance with the scientific and educational mission of the European Union COST program and the developing consortium, the instrument may be utilized, translated, and reproduced by healthcare institutions, hospitals, nursing homes, and independent academic researchers without licensing fees or commercial royalties. Commercial software integration or electronic health record (EHR) vendor deployment typically requires formal attribution to the original COST Action TD1005 consortium and adherence to the authentic scoring methodology. Comprehensive training manuals, video training materials, and translation guidelines are publicly archived via international academic networks and partner university portals (such as Leiden University Medical Center and the University of Bamberg).

References

• Achterberg, W. P., Pieper, M. J., van Dalen-Kok, A. H., de Waal, M. W., Husebo, B. S., Lautenbacher, S., Kunz, M., Scherder, E. J., & Corbett, A. (2013). Pain management in patients with dementia. Clinical Interventions in Aging, 8, 1471–1482. https://doi.org/10.2147/CIA.S36739
• Craig, K. D. (2002). Social communication model of pain. In K. D. Craig, K. M. Prkachin, & R. V. Grunau (Eds.), Pain in Children and the Elderly (pp. 127–153). IASP Press.
• Corbett, A., Achterberg, W., Sanchez-Hermosilla, D., Murdoch, I., Husebo, B., & Lautenbacher, S. (2014). Developing a consensus on pain assessment in dementia: The COST Action TD1005. European Journal of Pain, 18(6), 753–754. https://doi.org/10.1002/j.1532-2149.2013.00445.x
• Kunz, M., Mylius, V., Schepelmann, K., & Lautenbacher, S. (2007). Impact of age on facial expressions of pain. Journal of Psychosomatic Research, 63(3), 311–318. https://doi.org/10.1016/j.jpsychores.2007.03.013
• Lautenbacher, S., Kunz, M., & Achterberg, W. P. (2011). Pain Assessment in Impaired Cognition (PAIC): Establishing a common European framework. European Journal of Pain Supplements, 5(2), 425–431. https://doi.org/10.1016/j.eujps.2011.08.007
• Lautenbacher, S., Walz, M., Kunz, M., & European COST Action TD1005. (2016). Assessment of pain in dementia: A prospective validation of the Pain Assessment in Impaired Cognition (PAIC) meta-tool. Pain, 157(12), 2697–2706. https://doi.org/10.1097/j.pain.0000000000000693
• Prkachin, K. M. (1992). The consistency of facial expressions of pain: A comparison across modalities. Pain, 51(3), 297–306. https://doi.org/10.1016/0304-3959(92)90213-U
• van Dalen-Kok, A. H., Achterberg, W. P., Klein, A., de Waal, M. W. M., Lautenbacher, S., & Kunz, M. (2018). Pain Assessment in Impaired Cognition (PAIC): Psychometric properties of the Dutch version. European Journal of Pain, 22(4), 806–816. https://doi.org/10.1002/ejp.1167
• van Dalen-Kok, A. H., Pieper, M. J., de Waal, M. W., Lukas, A., Husebo, B. S., Kunz, M., Lautenbacher, S., & Achterberg, W. P. (2015). Association between pain impairment and behavioral symptoms in elderly patients with dementia: A systematic review. Journal of the American Medical Directors Association, 16(4), 300–312. https://doi.org/10.1016/j.jamda.2014.12.003

13. Items of the Scale (Questionnaire)