The Burden of Pruritus Associated With CKD: A Mixed Methods Analysis Among Patients Undergoing Dialysis.

Rationale & Objective: Despite its prevalence and distress to patients, chronic kidney disease-associated pruritus (CKD-aP) is poorly characterized, which may contribute to the condition's underdiagnosis and inadequate management. This study aimed to understand the symptom experience of patients with CKD-aP and the extent to which pruritus impacts their lives. Study Design: Mixed methods study including one-on-one qualitative interviews and completion of the Skindex-10 Questionnaire (measuring itch-related quality of life). Setting & Participants: A total of 23 patients undergoing hemodialysis and reporting pruritus at 4 dialysis centers in the United States. Analytical Approach: Interviews followed a semistructured guide that included targeted and follow-up questions to elicit discussion of patients' symptoms of pruritus, including frequency and variability, impact on activities of daily living, and emotional and social functioning. Interviews were digitally audio-recorded. A coding dictionary was developed from transcripts to analyze themes and concepts. Results: Participants described their itch with various terms, including "numbness," "pain," and "tingling" on their skin. Itch affected multiple areas but especially the back, usually occurred daily, and was often worse at night. For some, itching was a constant experience. Patients relieved their itch through scratching and various off-label treatments; some reported skin damage from excessive scratching and most indicated treatments provided limited relief. Pruritus considerably disrupted physical function, including sleep, daily activities, social functioning and relationships, and emotional and psychological wellbeing. All participants reported being bothered by their itching during the past week on the Skindex-10 Questionnaire. Limitations: All participants were from the United States, so the findings may not be generalizable to other countries. Conclusions: Although symptom experience varies considerably, CKD-aP causes severe distress for many patients undergoing hemodialysis and can profoundly impair their quality of life. The results of this study show the impact of itch from patients' perspectives and highlight the need for greater awareness and better management of this condition. Plain-Language Summary: Patients with chronic kidney disease often experience itching, or pruritus, but its importance to patients is regularly overlooked. This study used one-on-one interviews to investigate patients' experiences of chronic kidney disease-associated pruritus and how it impacts their lives. We found that participants experienced itch on various body areas and used different words to describe their itch (eg, "numbness" and "pain"). Some reported skin damage from excessive scratching, and many used off-label treatments and other interventions (eg, rubbing alcohol and multiple showers daily), which provided limited relief. For many, itching was experienced daily and severely disrupted sleep, daily activities, interactions with others, and mental wellbeing. These findings reveal chronic kidney disease-associated pruritus severely impacts patients and highlights the need for improved management of this condition.

Psychometric validation and meaningful change thresholds of the Worst Itching Intensity Numerical Rating Scale for assessing itch in patients with chronic kidney disease-associated pruritus.

BACKGROUND: Chronic kidney disease-associated pruritus (CKD-aP) is characterized by persistent itch that often leads to substantially impaired quality of life. The Worst Itching Intensity Numerical Rating Scale (WI-NRS) is a single-item patient-reported outcome measure in which patients indicate the intensity of the worst itching they experienced over the past 24 h. Here, we evaluated the content validity and psychometric properties of the WI-NRS and confirmed the threshold of meaningful change in hemodialysis patients with moderate-to-severe CKD-aP. METHODS: Content validity interviews were conducted in 23 patients. Psychometric properties of the WI-NRS were assessed using data from one phase 2 (N = 174) and two phase 3 (N = 848) clinical trials investigating an anti-pruritic treatment. Anchor-based methods were used to confirm meaningful within-patient change score thresholds in the phase 3 trial patients and mixed-method exit interviews (N = 70) contributed further insight. RESULTS: Content validity interviews indicated patients considered the WI-NRS to be straightforward, comprehensive, and relevant. Test-retest reliability was strong in both trial cohorts (intraclass correlation coefficients > 0.75). Construct validity analyses indicated high correlation between the WI-NRS and other measures of itch. Anchor-based analyses showed a reduction of ≥ 3 points from baseline score represented an appropriate clinically meaningful within-patient change on the WI-NRS. In the exit interviews, all patients with a reduction ≥ 3 points considered the change meaningful. CONCLUSIONS: The WI-NRS is a reliable, valid, and responsive measure of itch intensity for patients with moderate-to-severe CKD-aP. These results support its use to assess treatment efficacy and in clinical evaluation and management of pruritus in hemodialysis patients.

Itching is a distressing medical condition common in patients with chronic kidney disease, especially those undergoing hemodialysis. The itch often leads to skin damage due to a continuous and uncontrollable urge to scratch. It affects about 60% of hemodialysis patients and can be severe enough to seriously affect quality of life. At present, there are no approved therapies. To evaluate whether new treatments for itch are effective, clinicians need to assess if the intensity of itch decreases over time. However, because itch intensity can only be measured accurately by the person experiencing it, a measure is required that can be easily understood and used by patients. This study evaluated a scale in which patients mark a number between '0' (corresponding to no itch) and '10' (the worst itching imaginable), to describe the worst itch intensity they experienced over the last 24 hours. Using data from three clinical trials of a novel treatment for itch in patients undergoing hemodialysis with moderate-to-severe pruritus, we found that the scale was reliable in repeat-testing experiments, and mirrored other methods of measuring changes in itch. In interviews, patients said they found the scale straightforward and easy to complete. Our analysis and patients' opinions showed a 3-point reduction in itch intensity on the scale represented a meaningful improvement. These findings support the use of this scale to assess the efficacy of new treatments and in clinical evaluation and management of pruritus in patients with chronic kidney disease.

Validation of the shortened Hunter Syndrome-Functional Outcomes for Clinical Understanding Scale (HS-FOCUS).

BACKGROUND: The rare disease, Hunter Syndrome (mucopolysaccharidosis type II; MPS II), characterized by iduronate-2-sulfatase deficiency, has heterogeneous symptoms often including cognitive impairment (CI). To evaluate physical functioning and daily activity limitations of patients with MPS II, the multidomain shortened Hunter Syndrome-Functional Outcomes for Clinical Understanding Scale (HS-FOCUS) questionnaire was previously developed and preliminarily validated. Here we gather data in a dedicated prospective longitudinal observational study using direct responses to the shortened instrument and assess its psychometric properties further. METHODS: Interview data were collected from eligible self-reporting patients (≥ 12 years of age) or caregivers of patients using respective versions of the instrument at baseline and 2-4 weeks later. Internal consistency, test-retest reliability, convergent and discriminant validity, and validity of known groups were assessed. Participants also completed Child Health Questionnaire (CHQ), Health Utilities Index Mark 3, and Global Impression of Severity (GIS) questionnaires. RESULTS: All patients were male, consisting of 31 caregiver-reported patients (aged 3-26 years) and 20 self-reported patients (aged 12-58 years). Most (77.4%) caregiver-reported patients had CI. Both questionnaire versions demonstrated good internal consistency and test-retest reliability; Cronbach's alpha and intra-class correlation coefficients were > 0.70. Spearman's correlations demonstrated good convergent validity with moderate (> 0.3) to high (> 0.6) correlations of the HS-FOCUS total score with physical functioning, role/social-physical, and bodily pain domains of CHQ. The tool also differentiated between MPS II severity levels based on GIS scores. CONCLUSIONS: The shortened HS-FOCUS questionnaire was found to be a valid and reliable tool to assess the physical functioning impact of MPS II.

Patient-Reported Outcome and Observer-Reported Outcome Assessment in Rare Disease Clinical Trials: An ISPOR COA Emerging Good Practices Task Force Report.

BACKGROUND: Rare diseases (RDs) affect a small number of people within a population. About 5000 to 8000 distinct RDs have been identified, with an estimated 6% to 8% of people worldwide suffering from an RD. Approximately 75% of RDs affect children. Frequently, these conditions are heterogeneous; many are progressive. Regulatory incentives have increased orphan drug designations and approvals. OBJECTIVE: To develop emerging good practices for RD outcomes research addressing the challenges inherent in identifying, selecting, developing, adapting, and implementing patient-reported outcome (PRO) and observer-reported outcome (ObsRO) assessments for use in RD clinical trials. GOOD PRACTICES FOR OUTCOMES RESEARCH: This report outlines the challenges and potential solutions in determining clinical outcomes for RD trials. It follows the US Food and Drug Administration Roadmap to Patient-Focused Outcome Measurement in Clinical Trials. The Roadmap consists of three columns: 1) Understanding the Disease or Condition, 2) Conceptualizing Treatment Benefit, and 3) Selecting/Developing the Outcome Measure. Challenges in column 1 include factors such as incomplete natural history data and heterogeneity of disease presentation and patient experience. Solutions include using several information sources, for example, clinical experts and patient advocacy groups, to construct the condition's natural history and understand treatment patterns. Challenges in column 2 include understanding and measuring treatment benefit from the patient's perspective, especially given challenges in defining the context of use such as variations in age or disease severity/progression. Solutions include focusing on common symptoms across patient subgroups, identifying short-term outcomes, and using multiple types of COA instruments to measure the same constructs. Challenges in column 3 center around the small patient population and heterogeneity of the condition or study sample. Few disease-specific instruments for RDs exist. Strategies include adapting existing instruments developed for a similar condition or that contain symptoms of importance to the RD patient population, or using a generic instrument validated for the context of use. CONCLUSIONS: This report provides state-of-the-art solutions to patient-reported outcome (PRO) and observer-reported outcome (ObsRO) assessments challenges in clinical trials of patients with RDs. These recommended solutions are both pragmatic and creative and posed with clear recognition of the global regulatory context used in RD clinical development programs.

Psychometric evaluation of the 10-item Short Opiate Withdrawal Scale-Gossop (SOWS-Gossop) in patients undergoing opioid detoxification.

INTRODUCTION: The Short Opiate Withdrawal Scale (SOWS)-Gossop is a 10-item questionnaire developed to evaluate opioid withdrawal symptom severity. The scale was derived from the original 32-item Opiate Withdrawal Scale in order to reduce redundancy while providing an equally sensitive measure of opioid withdrawal symptom severity appropriate for research and clinical practice. The objective of this study was to examine the psychometric properties and provide score interpretation guidelines for the SOWS-Gossop 10-item version. METHODS: Blinded, pooled data from two trials assessing the efficacy of lofexidine hydrochloride in reducing withdrawal symptoms in patients undergoing opioid detoxification were used to evaluate the quantitative psychometric properties and score interpretation of the SOWS-Gossop. RESULTS: Five hundred fifty-five (N=555) observations were available at baseline with numbers decreasing to n=213 at day 7. Mean (standard deviation) SOWS-Gossop scores were 10.4 (6.86) at baseline, 8.7 (6.49) on day 1, 10.5 (7.21) on day 2, and 3.1 (3.95) on day 7. Confirmatory factor analysis indicated that the SOWS-Gossop items loaded on a single factor consistent with a single total score. Intra-class correlations (95% confidence interval) were 0.78 (0.70-0.85) between baseline and day 1, 0.84 (0.79-0.89) between days 4 and 5, and 0.88 (0.83-0.91) between days 6 and 7, demonstrating good test-retest reliability. Mean SOWS-Gossop scores varied significantly (p<0.0001) by Modified Clinical Global Impression severity groups supporting known-groups validity. Most correlations with conceptually similar instruments were over 0.4, providing evidence of construct validity. Results suggest that a change score of approximately 2-4 points is likely a small but meaningful improvement on the SOWS-Gossop Total Score. CONCLUSIONS: The findings of this study indicate that the SOWS-Gossop includes concepts that are relevant to patients' experiences with opioid withdrawal and has excellent psychometric properties. The SOWS-Gossop is an appropriate, precise, and sensitive measure to evaluate the symptoms of acute opioid withdrawal in research or clinical settings.

Content Validity of the Hypogonadism Impact of Symptoms Questionnaire (HIS-Q): A Patient-Reported Outcome Measure to Evaluate Symptoms of Hypogonadism.

BACKGROUND: Hypogonadism, or low testosterone, is a common disorder. There are currently no patient-reported outcome (PRO) instruments designed to comprehensively evaluate the symptoms of hypogonadism and to detect changes in these symptoms in response to treatment. OBJECTIVE: The purpose of this study was to develop a PRO instrument, the Hypogonadism Impact of Symptoms Questionnaire (HIS-Q) and to assess its content validity. METHODS: A literature review, expert clinician input, and qualitative concept elicitation with 39 male hypogonadism patients (four focus groups: n = 25; individual interviews: n = 14; mean age 52.3 ± 14.3 years) from the USA were used to develop the draft HIS-Q. Subsequent cognitive interviews (n = 29; mean age 51.5 ± 15.4 years) were used to evaluate content validity. RESULTS: Emergent discussion with participants yielded symptoms within the sexual, physical, energy, sleep, cognition, and mood domains. Low libido and tiredness were most commonly reported. The initial version of the HIS-Q includes 53 items that were consistently understood by the participants, who found the instrument to be relevant to their experiences with hypogonadism and comprehensive in the content coverage of symptoms. CONCLUSION: The HIS-Q is a comprehensive PRO measure of hypogonadism symptom severity in males. Its design elements, including the response options and recall period, were suitable, and content validity was confirmed.

What do we know about asthma triggers? a review of the literature.

OBJECTIVE: For patients with asthma, exacerbations and poor control can result from exposure to environmental triggers, such as allergens and air particulates. This study reviewed the international literature to determine whether a global checklist of common asthma triggers might be feasible for use as a research or management tool in clinical practice. METHODS: Literature published from 2002 to 2012 was identified through PubMed and EMBASE using the following search terms: asthma, asthma triggers, prevalence, among others. A total of 1046 abstracts were found; 85 articles were reviewed covering six continents (number of articles): Africa (1), Asia (22), Australia (1), Europe (27), North America (22), and South America (4). RESULTS: The literature consistently pointed to asthma triggers as one contributor to poor asthma control. Frequently cited triggers were similar across countries/regions and included allergens (particularly pollens, molds, dust, and pet dander), tobacco smoke, exercise, air pollutants/particulates, weather patterns/changes, and respiratory infections. Definitions of asthma triggers, how triggers are taken into account in definitions of asthma control, and scientific inquiry into optimal management techniques for triggers were inconsistent and sparse. CONCLUSIONS: Given the apparent importance of triggers in attaining and maintaining asthma control, empirical research concerning optimal trigger management is needed. Results demonstrate that asthma triggers are similar across continents, suggesting a global checklist of triggers for use in research and clinical practice would be feasible.

The humanistic burden of hereditary angioedema: Impact on health-related quality of life, productivity, and depression.

Hereditary angioedema (HAE) is a rare, autosomal dominant disorder characterized by recurrent acute attacks of swelling of the larynx, abdomen, and periphery. This study was designed to assess the humanistic burden of illness associated with HAE. HAE burden was assessed via a web-based survey of patients that solicited information on attack characterization, treatment, side effects, pain, and functional and emotional burden of disease management. In addition to HAE-specific sections, the survey used three standardized instruments to compare HAE patient data to normative (healthy) and chronic disease populations: the 12-Item Short Form (SF-12) Health Survey, the Work Productivity and Activity Impairment-General Health (WPAI-GH) questionnaire, and the Hamilton Depression Inventory-Short Form (HDI-SF). A total of 457 HAE patients responded to the survey (response rate, ∼19%). Patients reported significantly poorer health-related quality of life versus population norms, based on the SF-12 Physical Component Summary (mean, 43.7 versus 49.6; p < 0.001) and Mental Component Summary (mean, 42.6 versus 49.4; p < 0.001). HAE patients also had higher mean HDI-SF scores than population norms (8.1 ± 6.5 versus 3.1 ± 3.0; p < 0.001), with 42.5% of HAE patients scoring >8.5, indicative of depressive symptomatology. Productivity was also markedly impaired in all WPAI-GH categories, including 34% overall work impairment. Because of their most recent HAE attack, workers lost a mean of 3.3 days; students lost a mean of 1.9 days. HAE results in considerable humanistic burden to patients across physical and mental health domains; negatively impacts education, career, and work productivity; and compounds the substantial economic burdens that are reported separately.

Psychometric evaluation of the Medication Satisfaction Questionnaire (MSQ) to assess satisfaction with antipsychotic medication among schizophrenia patients.

The Medication Satisfaction Questionnaire (MSQ) is a single-item questionnaire which evaluates satisfaction with antipsychotic medication in schizophrenia patients. This study evaluated the reliability and validity for its use in research and clinical settings. Data pooled across treatment groups (control vs. Paliperidone ER) from a randomized 6-week study were used to conduct four psychometric assessments of the MSQ: (1) test-retest reliability, (2) convergent validity, (3) known-groups validity, and (4) minimally important difference (MID). This analysis included 191 randomized subjects. Test-retest reliability was evaluated for patients with no change in satisfaction from weeks 2 to 4 and weeks 4 to 6 (ICC=0.80; 0.83, respectively). Convergent validity was demonstrated through large correlations with Treatment Satisfaction Questionnaire for Medication (TSQM) global score (r=0.72-0.77), and through small correlations with variables measuring clinical symptoms and functioning (e.g., Positive and Negative Syndrome Scale (PANSS) total score [r=-0.30 to -0.17], CGI-S [r=-0.35 to -0.27], SF-36 Physical Functioning Score [r=0.18] and side effects and extrapiramidal measures (including UKU, ESRS-A, SAS). Mean MSQ scores were significantly different between those who completed and discontinued the study, and between different satisfaction groups based on TSQM, demonstrating good known-groups validity. MID estimates for the MSQ ranged from 0.47 (standard error of measurement) to 0.58 (anchor-based method). Results suggest that the MSQ has acceptable reliability and validity, making this single-item questionnaire appropriate and easy to use in clinical research and potentially in clinical practice. A 1-point change on the MSQ may be considered clinically meaningful.

Use of latent growth curve models for assessing the effects of darbepoetin alfa on hemoglobin and fatigue.

BACKGROUND: The relationship between darbepoetin alfa and fatigue in chemotherapy-induced anemia (CIA) patients is complex because of patients receiving transfusions and the mediating effect of hemoglobin. Latent growth models (LGMs) were used to examine simultaneously relationships among drug exposure, fatigue outcomes, covariates, and mediating factors. METHODS: Data from four CIA studies (AMG 20010145: small cell lung cancer, n=547; AMG 980297: lung cancer, n=288; AMG 20000161: lymphoproliferative malignancies, n=339; AMG 20030232: non-myeloid malignancies, n=320) were analyzed separately. Patients reported fatigue using the FACT-Fatigue. The effect of darbepoetin alfa on FACT-F changes mediated through hemoglobin changes was examined with LGMs controlling for transfusions, age, sex, baseline ECOG performance status, and health status (EQ-5D VAS). Model fit was assessed using multiple indices including the comparative fit index (CFI). RESULTS: Darbepoetin alfa increased hemoglobin levels which were associated with decreases in fatigue. Increases in hemoglobin were statistically significantly (p<0.05) related to decreases in fatigue in the studies (AMG 20030145: beta=0.28; AMG 980297: beta=0.46; AMG 20000161: beta=0.59; and AMG 20030232: beta=0.39). Darbepoetin alfa statistically significantly increased hemoglobin (AMG 20010145:beta=0.50, AMG 980297:beta=0.53, AMG 20000161:beta=0.47, and AMG 20030232:beta=0.30) while controlling for covariates. Model fit was acceptable (CFI> or =0.89) in all studies. CONCLUSIONS: Results indicate LGMs may be a valuable statistical method for modeling complex relationships among clinical and patient reported outcomes. A statistically significant effect of darbepoetin alfa on fatigue change through hemoglobin change occurred across four studies, after modeling the effects of transfusions, age, sex, EQ-5D VAS and ECOG.

Measurement of non-restorative sleep in insomnia: A review of the literature.

OBJECTIVE: Non-restorative sleep (NRS) is a core symptom of insomnia, typically defined as a subjective feeling of being unrefreshed upon awakening. NRS symptoms have been less consistently studied than other symptoms of insomnia, and there is no consensus regarding measurement of NRS. Given its subjective nature, patient-reported outcome (PRO) instruments are important for evaluating NRS symptom severity and treatment-related changes. The objective of this literature review was to identify PROs used in insomnia populations that purport to measure NRS, and to evaluate their psychometric characteristics. METHODS: A comprehensive review of PRO instruments used in insomnia was conducted; instruments were reviewed for NRS content by two independent reviewers; a total of 26 instruments identified to contain NRS content were retained for further review. RESULTS: Of the 26 instruments reviewed, 23 contained at least one item evaluating subjective nighttime aspects of NRS; 17 contained at least one item evaluating daytime aspects of NRS. Only the Sleep Assessment Questionnaire contained a specific NRS domain score. However, little published evidence was available regarding measurement properties of the NRS domain in insomnia populations. CONCLUSIONS: There is currently no reliable and well-validated PRO instrument available for specifically evaluating NRS symptom severity and response to interventions in insomnia populations. Reliable and valid measurement tools are needed to measure the symptom of NRS in insomnia.

Psychometric validation of two patient-reported outcome measures to assess symptom severity and changes in symptoms in hereditary angioedema.

PURPOSE: Hereditary angioedema (HAE) is a rare disorder characterized by highly variable, acute attacks of swelling at various anatomical locations. Clinical measures do not adequately assess the diversity of symptoms characteristic of an attack. Two disease-specific, patient-reported outcome measures were developed to comprehensively capture symptom severity and change: the Treatment Outcome Score (TOS) and the Mean Symptom Complex Severity (MSCS) score. METHODS: This study comprised a secondary analysis of pooled data from a randomized controlled trial to evaluate the psychometric properties, including reliability and validity, and minimally important difference (MID) of the TOS and MSCS score. RESULTS: HAE patients (n = 73) had a mean age of 33 years, and 60% were female. Test-retest evaluation demonstrated moderate to substantial agreement (ICCs = 0.53 for TOS; 0.62 for MSCS score). The TOS and change in MSCS score were moderately to highly correlated with a Global Improvement Measure at 4 h (TOS: r = 0.90; MSCS: r = -0.59). Anchor- and distribution-based analyses suggested that conservative estimates for MID are 30 points for TOS and -0.30 points for 4-h change in MSCS score. CONCLUSIONS: The psychometric tests performed here provide evidence of the reliability and validity of the TOS and MSCS for evaluating symptom severity and change in HAE patients. The TOS and MSCS score provide an example of measurement methodology that may be used to precisely capture symptom severity and change in a disease characterized by acute attacks.

Using the congestion quantifier seven-item test to assess change in patient symptoms and their impact.

Generally, nasal congestion is reported to be the most troublesome symptom of allergic rhinitis and has been shown to have negative effects on sleep, productivity, work, and school performance. A new patient-reported outcome (PRO) tool called the Congestion Quantifier Seven-Item Test (CQ7) was developed and shown to be a reliable and valid screening tool for nasal congestion. The purpose of this study was to assess the CQ7 as a tool for clinical use that can monitor changes in nasal congestion or determine if patients are showing meaningful improvement in symptoms. This study examined the responsiveness of the CQ7 to changes in nasal congestion and changes in relevant PRO to explore whether the CQ7 can serve as a monitoring tool and a valid screening tool for nasal congestion using latent growth curve models. Results showed that the CQ7 is sensitive to changes in patients' symptoms and their impact. Change in the CQ7 from baseline to day 15 was highly related to the change in symptom scores from baseline to day 15 (beta = -0.99); and regression coefficients for the relationships between the CQ7 and changes in the other PRO subscales also were very high (betas ranged from -0.79 to -0.95), lending evidence to support the use of the CQ7 as a monitoring tool. The large sizes of the coefficients suggest that the efficient, seven-item monitoring tool captures change in congestion very well. Analyses of responsiveness to change suggest that a three- to four-point improvement is meaningful to patients.

Reliability, validity, and responsiveness of the daily sleep interference scale among diabetic peripheral neuropathy and postherpetic neuralgia patients.

To evaluate the psychometric characteristics of the Daily Sleep Interference Scale (DSIS) in patients with painful diabetic peripheral neuropathy (DPN) or postherpetic neuralgia (PHN), a post hoc secondary analysis of data from eight randomized clinical trials (four DPN and four PHN) was performed. Data were pooled within patient populations when assessment weeks were the same. The DSIS was completed by 1,124 DPN and 1,034 PHN patients. Patient-reported outcomes, including a Daily Pain Diary, the Short-Form McGill Pain Questionnaire, SF-36 Health Survey, Profile of Mood States, MOS-Sleep Scale (MOS-SS), EQ-5D, and Patient Global Impression of Change, were used to validate the DSIS. Test-retest reliability was high for both samples (intraclass correlation coefficient>0.90). The DSIS showed good construct validity, with moderate to high correlations between the DSIS and weekly mean pain scores (r=0.48-0.80), MOS-SS sleep disturbance subscale (r=0.45-0.64), MPQ-SF Pain Experience (r=0.37-0.61), and VAS (r=0.42-0.72). The DSIS showed good discriminant validity in both groups; high and low MOS-SS sleep disturbance groups had significantly different DSIS scores (P<0.001). DPN patients who improved minimally on the Patient Global Impression of Change and in pain scores improved 1.5-2 DSIS points on average; for PHN, patient scores improved an average of 1-2 points. The DSIS demonstrated robust test-retest reliability, good construct and discriminant validity and responsiveness in painful DPN and PHN patients. A 1-2 point change on the DSIS might be interpreted as an important difference.