The importance of rating scales in measuring patient-reported outcomes

ABSTRACT: BACKGROUND: A critical component that influences the measurement properties of a patient-reportedoutcome (PRO) instrument is the rating scale. Yet, there is a lack of general consensusregarding optimal rating scale format, including aspects of question structure, the number andthe labels of response categories. This study aims to explore the characteristics of ratingscales that function well and those that do not, and thereby develop guidelines forformulating rating scales. METHODS: Seventeen existing PROs designed to measure vision-related quality of life dimensions weremailed for self-administration, in sets of 10, to patients who were on a waiting list for cataractextraction. These PROs included questions with ratings of difficulty, frequency, severity, and global ratings. Using Rasch analysis, performance of rating scales were assessed byexamining hierarchical ordering (indicating categories are distinct from each other and followa logical transition from lower to higher value), evenness (indicating relative utilization ofcategories), and range (indicating coverage of the attribute by the rating scale). RESULTS: The rating scales with complicated question format, a large number of response categories, orunlabelled categories, tended to be dysfunctional. Rating scales with five or fewer responsecategories tended to be functional. Most of the rating scales measuring difficulty performedwell. The rating scales measuring frequency and severity demonstrated hierarchical orderingbut the categories lacked even utilization. CONCLUSION: Developers of PRO instruments should use a simple question format, fewer (four to five) andlabelled response categories.     

Powder Compression Properties of Paracetamol,Paracetamol Hydrochloride,and Paracetamol Cocrystals and Coformers

The objective was to study the relationship between crystal structure, particle deformation properties, and tablet-forming ability for the monoclinic form of paracetamol (PRA), 2 cocrystals and a salt crystal of PRA in addition to 2 coformers (oxalic acid and 4,4′-bipyridine). Thus, the structure–property–performance relationship was investigated. Analytical powder compression was used for determination of effective plasticity, as inferred from the Heckel yield pressure and the Frenning parameter, and the elastic deformation was determined from in-die tablet elastic recovery. The plasticity could not be linked to the crystal lattice structure as crystals containing zig-zag layers displayed similar plasticity as crystals containing slip planes. In addition, crystals containing slip planes displayed both high and low plasticity. The mechanical properties could not be linked to the tablet-forming ability as the tablet tensile strength, unexpectedly, displayed a tendency to reduce with increased plasticity. Furthermore, the elastic deformation could not explain the tablet-forming ability. It was concluded that no relationship between structure–property–performance for PRA and its cocrystals and salt could be established. Thus, it was indicated that to establish such a relationship, an improved knowledge of crystallographic structure and interparticle bonding during compaction is needed.     

Mitomycin-C-augmented trabeculectomy for neovascular glaucoma. A preliminary report

PURPOSE: This study aimed to investigate the safety and efficacy of trabeculectomy with intraoperative mitomycin C (MMC) in the management of eyes with neovascular glaucoma (NVG). METHODS: Fifteen eyes of 14 patients with NVG were included in the study. NVG was secondary to central retinal vein occlusion (3 eyes), hemiretinal vein occlusion (2 eyes), proliferative diabetic retinopathy (8 eyes), branch retinal vein occlusion (1 eye) and idiopathic (1 eye). Preoperative retinal ablation was performed in eyes with evidence of posterior segment ischaemia. Following this, all eyes underwent trabeculectomy with intraoperative MMC (0.4 mg/ml for 3 minutes). Clinical outcome assessment included visual acuity, intraocular pressure (IOP), bleb appearance, identification of complications and antiglaucoma medications required to control IOP. RESULTS: The mean IOP decreased from 38.6 +/- 12.9 mmHg (range, 15-64 mmHg) to 17.4 +/- 9.33 mmHg (range, 4-34 mmHg) (P = 0.001). Preoperative visual acuity ranged from light perception to 6/9 in the affected eye. Thirteen (86.6%) of 15 eyes improved vision or retained preoperative vision, one (6.7%) eye lost light perception and one (6.7%) eye developed tractional retinal detachment two years after trabeculectomy. Ten (66.7%) of 15 eyes were classified as surgical success with a mean follow-up of 28.6 +/- 26.3 months (range, 2-82 months). None of the patients developed choroidal haemorrhage, hypotony maculopathy, late onset bleb leak or endophthalmitis. CONCLUSION: Trabeculectomy with intraoperative MMC is a good treatment modality in the management of eyes with NVG.     

The importance of rating scales in measuring patient-reported outcomes

Background

Discrepancy between self-reports and parent-proxy reports of adolescent health-related quality of life (HRQoL) has been repeatedly acknowledged in the literature as the proxy problem. However, little is known about the extent and direction of this discrepancy. The purpose of this study is to explore to what extent and in what direction HRQoL self-reports of adolescents with chronic conditions and those of their parents differ.

Methods

A cross-sectional survey was conducted among adolescents suffering from chronic conditions and their parents. Socio-demographic and disease-related characteristics were collected and information about consequences of the chronic condition was assessed. HRQoL was measured with KIDSCREEN-10 and DISABKIDS condition generic measure (DCGM-10). Agreement was analysed through defining a threshold of agreement based on half of the standard deviation of the HRQoL score with the highest variance. Agreement occurred if the difference between adolescent and parent scores was less than or equal to half of the standard deviation. Intra-class correlation coefficients and Bland-Altman plots were also computed. The characteristics associated with direction of disagreement were statistically tested with one-way ANOVA and Chi-square tests.

Results

584 paired HRQoL scores were obtained. Ratings from both adolescents and parents were high, compared to European norm data. Differences between adolescents and parents were statistically significant, yet relatively small. Disagreement existed in both directions: in 24.5% (KIDSCREEN-10) and 16.8% (DCGM-10) of the cases adolescents rated their HRQoL lower than did their parent, while in 32.2% (KIDSCREEN-10) and 31.7% (DCGM-10) of the cases the opposite was true. Adolescent's age, educational level and type of education, parent's educational level, number of hospital admissions and several other disease-related factors influenced direction of disagreement.

Conclusions

In a reasonable proportion of cases the adolescent and parent agreed on the adolescent's HRQoL (43-51% of the cases) and most disagreement tended to be minor. Thus, the proxy problem may be smaller than presented in the literature and its extent may differ per population. As adolescents are expected to become partners in their own health care, it is recommended to focus on adolescents' own perceptions of HRQoL.     

The pancreas and tuberculosis: a diagnostic challenge.

Pancreatic tuberculosis is often mistaken for malignancy and can pose a diagnostic challenge. A high degree of suspicion is necessary to diagnose this condition which responds well to anti-tuberculosis treatment (ATT). Fine-needle aspiration cytology helps to differentiate malignancy from treatable conditions like tuberculosis. Records of four patients treated for pancreatic tuberculosis between 1997 and 2006 were studied. All patients had a pancreatic mass which was suspected to be malignant at imaging. The diagnosis of tuberculosis was established by FNAC in one case and after laparotomy in one; two had tuberculosis of other systems. All showed good response to ATT which included resolution of the pancreatic mass over mean follow up of 2 years. We suggest that all inoperable masses of the pancreas should be subjected to FNAC to rule out treatable conditions like pancreatic tuberculosis.     

Formula for calculating standard liver volume in Indians

Aim  

To assess the validity of standard liver volume (SLV) calculated using various formulae in the Indian population.     

Outcome after repair of cor triatriatum

Cor triatriatum represents <0.1% of all congenital cardiac malformations. Symptoms in patients with cor triatriatum are related to pulmonary venous obstruction and pressure loading of the right side of the heart. The aim of this study was to describe our institutional experience with repair of cor triatriatum. From June 1963 to June 2010, 65 patients underwent repair at a median age of 7.2 months (range 2 days to 47.6 years). Among these patients, 49 (75%) had associated congenital heart defects. Atrial septal defect (n = 29), ventricular septal defect (n = 15), partially or totally anomalous pulmonary venous return (n = 14), mitral valve abnormalities (n = 11), and supravalvar mitral ring (n = 5) were the most common associated defects. Surgical treatment consisted of excision of the membrane, along with additional procedures in 47 patients (72%). Five patients had new postoperative supraventricular arrhythmias. During a median follow-up period of 5.4 years, no patients underwent reintervention for recurrent left atrial obstruction, 7 patients were noted to have minor residual cor triatriatum without obstruction, and 8 patients (including 4 diagnosed before cor triatriatum repair) had pulmonary vein stenosis, 6 of whom underwent intervention for that reason. In conclusion, in this large surgical series of patients who underwent repair of cor triatriatum, there were no cases of significant residual or recurrent cor triatriatum. Although the association between cor triatriatum and pulmonary vein stenosis has been described previously, the relative frequency of this condition in our cohort (>10%, including patients diagnosed before and after cor triatriatum repair) is noteworthy. Abnormalities of the mitral valve and a supravalvar mitral ring were also seen more often than the existing research would suggest, which may be another important consideration in evaluating and following these patients.