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PubMed2002

Psychometric evaluation of the Demands of Immigration Scale with Taiwanese-Chinese immigrants: a pilot study.

BACKGROUND: Each year thousands of people move across national borders and become immigrants of another country. They face several demands and sources of distress during resettlement. The Demands of Immigration (DI) Scale developed by Aroian et al. (1998), is the only instrument available to nurses (and other clinicians and researchers) to measure immigration-specific distress. This scale, however, is written in English and has only been tested with former Soviet immigrants in the Boston area of United States of America (USA) for psychometrics. AIM: This instrumentation pilot study is designed to evaluate the readability and psychometric properties of the Chinese version of the DI Scale. INSTRUMENT: This selected scale is a 23-item, 6-point Liket type scale. Six dimensions are included: loss, novelty, occupation adjustment, language accommodation, discriminations, and not feeling at home. High scores indicate high levels of distress related to the demands of immigration. METHODS: The study uses a descriptive, cross-sectional design with a multimethod approach. Seventy-three Taiwanese-Chinese immigrants (> or = 18 years) in the USA responded to the scale and a demographic questionnaire. Eighteen of them contributed to the interview data that were collected for assessing content validity of the scale. Observations during the interviews and participants' questions were also documented for the evaluation. Scale format, wording of items, distribution of responses, internal consistency, test-retest reliability, content validity, and construct validity are examined. FINDINGS AND CONCLUSION: Analyses suggest that the Chinese version is easy to read and understand. The internal consistency and test-retest reliability are satisfactory. This scale could be used with Taiwanese-Chinese immigrants as a generic measure of immigration-related distress. Nonetheless, three main problems with its use with Taiwanese-Chinese immigrants and Chinese immigrants at large are revealed in the study. Each problem is discussed. Suggestions for further development of the Chinese DI Scale are addressed.

Adult↗
PubMed1990

A multitrait-multimethod analysis of the MCMI-II clinical syndrome scales.

Multitrait-multimethod procedures and factor analyses were utilized to assess convergent/discriminant validity of the revised version of the Millon Clinical Multiaxial Inventory (MCMI-II) clinical syndrome scales and effects of item overlap on scale performance. Except for the Delusional Disorder Scale (PP), convergent validity was supported, but poor discriminant validity was found for the Alcohol Dependence (B) scale, Drug Dependence (T) scale, and Scale PP. Item overlap did not influence performance for many scales. In fact, results indicate that some scales, such as Bipolar:Manic (N), may perform better in overlapping form, whereas others, such as Somatoform (H) and Scales B and T, are most affected by item overlap. Factor structure was generally stable, regardless of whether overlapping or nonoverlapping scales were utilized. However, substance abuse/dependence emerged as an independent factor when common item artifact was removed. Findings are discussed in terms of their implications for clinical practice and further research.

Adult↗
PubMed1997

Functional assessment scales in detecting dementia.

AIM: to evaluate the use of different functional scales in detecting dementia in a population study. METHODS: the study is part of the Helsinki Ageing Study. A random sample of 795 subjects aged 75 (n = 274), 80 (n = 266) and 85 years (n = 255) was taken. The prevalences of dementia (DSM-III-R criteria) in these age groups were 4.6, 13.1 and 26.7% respectively. The functional scale scores were known for 71% of the non-demented and 66% of the demented subjects. A structured questionnaire completed by a close informant included four functional scales: the index of activities of daily living (ADL), the modified Blessed dementia scale (DS), the instrumental activities of daily living scale (IADL) and the Functional Assessment Questionnaire (FAQ). RESULTS: all the functional scales discriminated demented from non-demented subjects. Based on receiver operating characteristics analysis, the area under the curve (95% confidence interval) was 0.90 (0.80-0.94) for the ADL, 0.94 (0.87-0.97) for the DS, 0.95 (0.90-0.98) for the IADL and 0.96 (0.92-0.98) for the FAQ. The effects of age, sex and education in detecting dementia were minor or non-existent in the ADL, DS and FAQ scales, but age had an effect on the performance of the IADL scale. All the scales detected even mild dementia adequately. CONCLUSIONS: functional scales can be used in detecting dementia when functional assessment is already used for other purposes, such as among elderly primary care patients.

Activities of Daily Living↗
PubMed2006

Reliability and validity of the Pediatric Intensity Level of Therapy (PILOT) scale: a measure of the use of intracranial pressure-directed therapies.

OBJECTIVE: To test the reliability and validity of the Pediatric Intensity Level of Therapy (PILOT) scale, a novel measure of overall therapeutic effort directed at controlling intracranial pressure (ICP) in the setting of severe (Glasgow Coma Scale of <or= 8) pediatric traumatic brain injury (TBI). DESIGN: Case-control study via retrospective review of medical records. SETTING: Tertiary-care, university-based children's hospital intensive care unit. PATIENTS: Randomly selected patients <or=18 yrs old admitted to the intensive care unit in 2002-2003 with severe TBI (cases: group 1, n = 27), mild-moderate TBI (control: group 2, n = 30), extracranial trauma (control: group 3, n = 29), or nontraumatic illnesses (control: group 4, n = 27). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A 38-point scale was developed to quantify daily ICP-directed therapeutic effort. All currently recommended therapies are represented. Demographic and physiologic data were collected on all patients. A total of 24 of 27 patients with severe TBI received ICP-directed therapy; three did not because of judgments of futility. No control patients received ICP-directed therapy. The PILOT scale score was assessed for the first 7 days posttrauma or postadmission. Interrater reliability was 0.91 (intraclass correlation coefficient) and intrarater reliability was 0.94. The highest PILOT scale scores were in patients with severe TBI (11.7 +/- 5.6 vs. 1.3 +/- 1.7 vs. 2.0 +/- 2.1 vs. 1.9 +/- 1.8 for groups 1, 2, 3 and 4, respectively [mean +/- sd]; p < .001 by analysis of variance/Bonferroni). Patients with severe TBI who received ICP-directed therapy had higher PILOT scale scores (12.6 +/- 5.3 vs. 5.0 +/- 3.0, p = .001) than those who did not. Pearson's correlation coefficients of mean PILOT scale scores with measures of injury severity, outcome, and ICP were as follows: Glasgow Coma Scales score, -0.73 (p < .001); overall Injury Severity Score, 0.37 (p < .001); Injury Severity Score (head component only), 0.53 (p < .001); 6-month Glasgow Outcome Scale, -0.26 (p = .006); ICP burden (hours per day with ICP above treatment threshold), 0.59 (p = .002); and mean ICP, 0.41 (p = .044). CONCLUSIONS: The PILOT scale score can be obtained retrospectively and has good reliability. It can discriminate patients receiving ICP-directed therapy, even among patients with severe TBI, and correlates with measures of injury severity, outcome, and ICP in an expected way. Thus, it seems to be a valid measure of the use of ICP-directed therapy, although prospective, multiple-center validation is recommended.

Brain Injuries↗
PubMed1993

The convergent and discriminant validity of the Chapman Scales.

Our study investigated the convergent and discriminant validity of five of Chapman's Schizotypia Scales (i.e., Physical Anhedonia, Revised Social Anhedonia, Perceptual Aberration, Magical Ideation, and Impulsive Nonconformity; L.J. Chapman, J.P. Chapman, & Raulin 1976, 1978; Eckblad & L.J. Chapman, 1983) and Meehl's Schizoidia Scale (Meehl, 1964) within a sample of 50 personality disordered subjects, many of whom possessed schizotypic traits. It was hypothesized in part that all five of the Chapman scales and the Schizoidia Scale would correlate with the schizotypal personality disorder; the Physical Anhedonia and Revised Social Anhedonia Scales would correlate with the schizoid personality disorder, whereas the Magical Ideation and Perceptual Aberration Scales would not; the Physical and Revised Social Anhedonia Scales would not correlate with the avoidant personality disorder; and the Impulsive Nonconformity Scale would correlate with the borderline and antisocial personality disorders. Only the hypotheses concerning the avoidant personality disorder and the Schizoidia Scale were not supported. The findings remained even when the effects of state anxiety and state depression were controlled. Implications of the findings with respect to the validity of the Chapman and Schizoidia Scales and the personality disorders are discussed.

Adult↗
PubMed1998

The development of a scale to measure concepts of schizophrenia: experience among Brazilian psychiatrists.

INTRODUCTION: Among psychiatric disorders schizophrenia is often said to be the condition with the most disputed definition. The Bleulerian and Schneiderian approaches have given rise to diagnostic formulations that have varied with time and place. Controversies over the concept of schizophrenia were examined within European/North American settings in the early 1970s but little has since been reported on the views of psychiatrists in developing countries. In Brazil both concepts are referred to in the literature. A scale was developed to measure adherence to Bleulerian and Schneiderian concepts among psychiatrists working in S. Paulo. METHODOLOGY: A self-reported questionnaire comprising seventeen visual analogue-scale statements related to Bleulerian and Schneiderian definitions of Schizophrenia, plus sociodemographic and training characteristics, was distributed to a non-randomised sample of 150 psychiatrists. The two sub-scales were assessed by psychometric methods for internal consistency, sub-scale structure and test-retest reliability. Items selected according to internal consistency were examined by a two-factor model exploratory factor analysis. Intraclass correlation coefficients described the stability of the scale. RESULTS: Replies were received from 117 psychiatrists (mean age 36 (SD 7.9)), 74% of whom were made and 26% female. The Schneiderian scale showed better overall internal consistency than the Bleulerian scale. Intra-class correlation coefficients for test-retest comparisons were between 0.5 and 0.7 for Schneiderian items and 0.2 and 0.7 for Bleulerian items. There was no negative association between Bleulerian and Schneiderian scale scores, suggesting that respondents may hold both concepts. Place of training was significantly associated with the respondent's opinion; disagreement with a Bleulerian standpoint predominated for those trained at the University of S. Paulo. CONCLUSIONS: The less satisfactory reliability for the Bleulerian sub-scale limits confidence in the whole scale but on the other hand this questionnaire contributes to the understanding of the controversy over Bleulerian and Schneiderian models for conceptualisation of schizophrenia, the former requiring more inference and therefore being prone to unreliability.

Adult↗
PubMed2002

[A depression rating scale for the ward].

BACKGROUND: The aim of the present study was to develop a quantitative rating scale for depression based on observations in the ward and one that can be administered by the nursing staff. MATERIALS AND METHODS: Based on a literature survey and existing depression rating scales, a new rating scale was developed especially suited for use in inpatient care. The patients were rated simultaneously with the Beck Depression Inventory (BDI) and Clinical Global Impression (CGI). Estimation of construct validity, criterion validity, and item bias was performed with Rasch analysis and analysis of correlation. RESULTS: Statistical analysis revealed that the scale consisted of two sub-scales for mood and behaviour. One item had to be omitted as it was not homogeneous with either of the two sub-scales. DISCUSSION: The present depression rating scales rely on ward observations of patients during admission. This might be the reason why the items concerning behaviour are so strongly represented in this scale. Good correlations were found between the different scales, except for the score on BDI and the sub-scale concerning behaviour. This may be explained by the fact that the BDI is the patient's own judgement of cognitive function and mood. The observations in the ward are to a greater extent built on observation of patient behaviour. It can be used routinely on the psychiatric ward.

Adult↗
PubMed2003

[Neuroticism in the elderly. The utility of the shortened DPQ-scales].

This article reports on the relation between aging and personal adjustment. Current personality scales are not developed for older persons. Scales contain items which are not valid for an aging population and contain too many items for administration in older populations. As part of the Longitudinal Aging Study Amsterdam (LASA) Neuroticism in older persons was measured with a shortened version of the Inadequacy (IN) and Social Inadequacy (SI) scales of the Dutch Personality Questionnaire (DPQ). The utility of these shortened scales was assessed based on internal consistency, inter-item correlations, test-retest reliability and factor analysis. The consistency of the personality dimension Neuroticism was assessed based on cohort-differences and a 6-year longitudinal comparison. The research-population contained 2118 respondents at baseline, aged between 55 and 85 years, 49% were male and they were not living in an institution. The shortened scales appeared to be reliable and valid instruments to measure Neuroticism in the elderly. The gaining of time due to the administration of the shortened scales enlarges the feasibility of the scales for measuring Neuroticism in older persons. Results showed no significant age-difference on the IN-scale, but revealed a significant difference on the SI-scale (p < .01). The 65+ elderly (65-74 and 75-85) have higher scores on Social Inadequacy than the youngest elderly (55-64). Longitudinal analyses showed an interaction between age at baseline and the stability and change of the level of Neuroticism. On both scales the youngest age-group showed a significant decline in mean level of Neuroticism (p < .01). The mean level of Social Inadequacy in the oldest age-group showed an increase during the 6-year follow-up period (p < .05). However, the differences were very small. Future research is needed to assess the effect of related variables on Neuroticism in older persons.

Age Factors↗
PubMed1980

Validation of the General Practitioner Clinical Research Group 11-item depression scale.

In trials performed by the General Practitioner Clinical Research Group two rating scales have been employed extensively to measure depression. One includes some 17 target symptoms whilst the second is a shorter scale of 11 items. Although extensively used, neither scale has been validated against other measures of depression. An attempt was made to validate the 11-item scale, completed by the physician, against the Zung self-rating depression scale and the Wakefield Inventory, both patient-completed scales. Using thirty depressed patients the correlation between the 11-item scale and the Zung was 0.59 and between the 11-item scale and the Wakefield it was 0.5. Surprisingly, although the two scales are patient-completed and purport to measure the same thing, the correlation between the Zung and the Wakefield scales was only 0.69. All the correlations were statistically significant at the 1% level.

Adult↗
PubMed1998

[Validation of the prognostic accuracy of neurosurgical admission scales after rupture of cerebral aneurysms].

The course of 185 patients operated for a ruptured intracranial aneurysm at the University of Saarland between 1991 and 1993 has been followed up. The main emphasis of the investigation was placed on the scrutiny of the coma scales on admission (Hunt & Hess-Scale, Glasgow Coma Scale and WFNS-Scale [= World Federation of Neurological Surgeons]) with regard to the outcome. Outcome was defined as the patients' state six months after aneurysm rupture according to the Glasgow Outcome Scale. The sensitivities, specifities and predictive values of almost all scale grades were poor. The Hunt&Hess-Scale was the one with the best correlation. By half the patients with the worst scale grades on admission had a good outcome. A gradation of the outcome with regard to the middle admission grades has not been identified. These observations have been demonstrated by using ROC (Receiver Operating Characteristic)-curves. The admission scales are not suitable to give a definite prognosis and do not justify any decision neither pro nor contra an operation. A lot of parameters besides the neurological findings have an effect on the prognosis. Additionally, unexpected complications may occur in the pre- and postoperative phase. The score values determined at the day of operation have shown a more precise prognosis than the values determined immediately after hospitalization. Therefore the evaluation of the most relevant phase could improve the prognostic value of the scales.

Adult↗
PubMed1998

[Measurement of anxiety state in women: a short-form scale].

BACKGROUND: Clinical epidemiology and psychosocial studies often take into account the measurement of anxiety. Our objective was to develop and validate a short form scale of anxiety state from the Spielberger's State Trait Anxiety Inventory (STAI-Y), one of the most widely used scales. METHODS: This study was carried out on French samples of women with different levels of anxiety. The first step was to select from the original 20-items scale, the items susceptible to compose two short forms scales: an 8-items (18-STAI) and a 5-items (15-STAI) one. It was carried out on patients attending cancer genetic clinics (n1 = 160, n2 = 41). The second step was carried out on 3 other samples of women (n3 = 150, n4 = 167, n5 = 105) and measured the psychometric characteristics of the short-form scales obtained previously. RESULTS: The correlation coefficients between the short-forms and the complete 20-items form were very high (> 0.90) in particular for the 18-STAI (r > 0.95). Both short forms are sensitive to change. The internal consistency measured by Cronbach-alpha was comparable to the original scale. The results obtained with the 18 scale and another 10 items Spielberger's short-form scale are comparable and better than those with the 15 scale. CONCLUSION: The 18 French short-form scale, balanced with positive and negative items, can be recommended for the measurement of state anxiety when the complete form cannot be used.

Adult↗
PubMed2000

Concordance between ratings using different scales for the same variable.

Qualitative variables are commonly measured by means of different types of rating scales that produce ordered categorical data. The number of response categories in a scale can be chosen arbitrarily according to different operational definitions of the attribute to be measured. In the present paper classical measures based on the difference between the probabilities of concordant and discordant pairs of classifications were compared with a novel approach for assessment of order consistency between rating scales. In the new approach, illustrated by an assessment of pain, the concordant and discordant pairs are related to the pattern of total order consistency, irrespective of the scaling and the categorical distributions. The level of order consistency between a visual analogue scale (VAS) and a discrete scale for the same variable was evaluated. The non-linear properties of VAS assessments were demonstrated. The inter-scale consistency between the discrete scale and different approaches to grouping VAS responses into discrete scales showed that equidistant rescaling of VAS assessments resulted in an inter-scale bias.

Calibration↗
PubMed1984

Measuring family functioning with the MMPI: a reliability and concurrent validity study of three MMPI family scales.

Examined the utility of three MMPI family scales. Three MMPI family scales and three criterion family scales were administered to 110 undergraduates. Internal consistency coefficients were calculated for each MMPI family scale. Relationships between the MMPI family scales and the criterion scales are examined by a correlational analysis. Findings suggest that the MMPI family scales are reliable and concurrently valid measures of an individual's perception of interpersonal family relationships. Procedures for scoring and interpreting the MMPI family scales are examined. The findings also indicate which MMPI family scale is the overall best scale.

Adolescent↗
PubMed1992

Avian scale development. XVII: The epidermis of the scaleless (sc/sc) anterior metatarsal skin is determined, but the dermis lacks permissive cues for the patterned expression of the determined state.

Embryos homozygous for the gene scaleless (sc/sc) completely lack scutate scales and the beta strata which characterize terminal differentiation of the scale ridges located on the anterior metatarsal region of the foot. Although the sc/sc epidermis cannot undergo scale morphogenesis, it can respond to the inductive dermal ridges of normal scutate scales by generating beta strata. Recently, we discovered that the anterior metatarsal epidermis of normal embryos becomes committed to the formation of beta strata prior to morphogenesis of definitive scale ridges. Here, we examined the possibility that the sc/sc anterior metatarsal epidermis also becomes determined, i.e., committed to scutate scale-specific terminal differentiation. Experimental tissue recombinants were used to assess the ability of the sc/sc epidermis to generate beta strata. The results show that the germinative cells of the 15-day sc/sc epidermis are committed to generating beta strata, even though they have not undergone scutate scale morphogenesis. Thus, the mechanisms involved in establishing epidermal determination must differ form those regulating scale morphogenesis. In addition, we examined the formation of patterned, permissive cues in the anterior metatarsal and footpad dermises of sc/sc embryos. Analysis of recombinants showed that both the 15- and 20-day dermises from the sc/sc anterior metatarsal region fail to provide cues for beta stratum formation, when associated with the determined 15-day scutate scale epidermis. Likewise, the 15-day sc/sc footpad dermis cannot support beta stratum formation. However, 20-day sc/sc footpad dermis is able to support the generation of a few abnormally patterned beta strata, demonstrating that sc/sc dermis which has experienced even limited morphogenesis is able to provide permissive cues for the terminal differentiation of the scutate scale epidermis.

Animals↗
PubMed1994

The Numbing Scale: psychometric properties, a preliminary report.

This study explored the psychometric properties of a new self-report instrument, The Glover Numbing Scale. The scale measures a variety of behaviors reported by individuals experiencing an inability to access feelings other than hostility and rage. The scale was administered to inpatient Vietnam combat veterans with post-traumatic stress disorder (PTSD, n = 323), PTSD diagnosed Veterans Affairs (VA) outpatient and veterans' outreach center veterans (n = 208), two Vietnam veteran noncombat groups (n = 45), two psychiatric noncombat controls (anxiety disorder, n = 40; major depressive disorder, n = 31), and a nonpsychiatric never-in-Vietnam veteran control group (n = 48). Reliability information suggested that the scale was internally consistent with good test-retest correlations. Convergent and discriminant validations were assessed based on the pattern of the scale's correlations with relevant Minnesota Multiphasic Personality Inventory (MMPI) scales. The contrasting pattern of correlations provided by a subgroup of veterans who reported always feeling dead or shut down was highlighted. Principal component analysis resulted in a five factor solution that provided evidence for the scale's factorial validity. Numbing Scale scores discriminated levels of psychopathology within the veteran population. PTSD outreach center veterans' sum scores and item scores on the Numbing Scale were more similar to responses of anxiety disorder patients than to major depressive disorder patients. Overall, the findings strongly support the clinical application of the Numbing Scale.

Adult↗
PubMed1994

Light and TEM study of nonregenerated and experimentally regenerated scales of Lepisosteus oculatus (Holostei) with particular attention to ganoine formation.

BACKGROUND: The structure of nonregenerated and experimentally regenerated scales of the holostean fish Lepisosteus oculatus and the events taking place before and during ganoine deposition on the scale surface were studied. The aim of this study was to answer the question of the origin of the ganoine in lepisosteids, the scales of which are devoid of dentine, and to compare them to ganoine formation in polypterid scales and to enamel formation in teeth. METHODS: Two adult specimens were used and the scale structure was studied using light and transmission electron microscopy. Regeneration was used as an alternative to the lack of developmental stages and to induce ganoine deposition on the scale surface. RESULTS: Nonregenerated scales are composed of a thick, avascular bony plate capped by ganoine that is covered either by the epidermis or by dermal elements. The ganoine surface is separated from the covering soft tissues by an unmineralized layer, the ganoine membrane. During the first 2 months of regeneration, the bony plate forms. It differs from the bony plate of nonregenerated scales only by its large, woven-fibered central region and by the presence of numerous vascular canals. Shortly before ganoine deposition, the osteoblasts cease their activity and an epithelial sheet comes to contact them and spreads on the bony surface. This epithelial sheet is connected to the epidermis by a short epithelial bridge only and is composed of two layers: the inner ganoine epithelium (IGE), in contact with the bone surface and composed of juxtaposed columnar cells that synthesize the ganoine matrix, preganoine; the outer ganoine epithelium (OGE), composed of elongated cells, the surface of which is separated from the overlying dermal space by a basal lamina. Isolated patches of preganoine are deposited by the IGE cells in the upper part of the osteoid matrix of the scale. The interpenetrated preganoine and osteoid matrices constitute an anchorage zone between ganoine and bone. Preganoine patches fuse and a continuous layer of preganoine is progressively synthesized by the IGE cells. Preganoine progressively mineralizes to become ganoine. CONCLUSIONS: The processes of ganoine formation are similar to those known for the ganoine in the polypterid scales and to those described for enamel deposition in teeth. Ganoine is enamel.

Animals↗
PubMed1995

The sense of coherence scale in patients with rheumatoid arthritis.

OBJECTIVE: To analyze Antonovsky's Sense of Coherence (SOC) Scale, in 828 patients with rheumatoid arthritis (RA) from 15 private rheumatology practices. This scale is designed to evaluate strengths within individuals that allow them to select appropriate strategies to deal with stressors; both the total 29-item (SOC-29) total scale and a 13-item (SOC-13) short form of the 29-item scale were analyzed. METHODS: Data were collected through mailed self-report questionnaires as a component of a long-term monitoring program. Internal consistency was evaluated according to Cronbach's alpha. Split-halves reliability was estimated according to the Spearman-Brown prophecy formula. Associations of the SOC-29 and the SOC-13 scale scores with demographic, clinical, and psychological variables were analyzed according to Pearson product moment correlations. RESULTS: Lower SOC-29 and SOC-13 scale scores were correlated significantly with higher scores for difficulty in performing activities of daily living (ADL), a visual analog pain scale score, global health status, and perceived learned helplessness. The levels of correlation for these variables suggest that each measure represents a construct that differs from the SOC. Lower scale scores were also correlated significantly with fewer years of formal education, adjusted for age, sex, and disease duration. CONCLUSIONS: The SOC-29 and SOC-13 scales are reliable and valid in patients with RA. The SOC scale explained in part variation in clinical status in patients with RA. The SOC-13 provides utility comparable to the SOC-29 in patients with RA.

Activities of Daily Living↗
PubMed2005

Robust scale-up of dead end filtration: impact of filter fouling mechanisms and flow distribution.

Robust design of a dead end filtration step and the resulting performance at manufacturing scale relies on laboratory data collected with small filter units. During process development it is important to characterize and understand the filter fouling mechanisms of the process streams so that an accurate assessment can be made of the filter area required at manufacturing scale. Successful scale-up also requires integration of the lab-scale filtration data with an understanding of flow characteristics in the full-scale filtration equipment. A case study is presented on the development and scale-up of a depth filtration step used in a 2nd generation polysaccharide vaccine manufacturing process. The effect of operating parameters on filter performance was experimentally characterized for a diverse set of process streams. Filter capacity was significantly reduced when operating at low fluxes, caused by both low filtration pressure and high stream viscosity. The effect of flux on filter capacity could be explained for a variety of diverse streams by a single mechanistic model of filter fouling. To complement the laboratory filtration data, the fluid flow and distribution characteristics in manufacturing-scale filtration equipment were carefully evaluated. This analysis identified the need for additional scale-up factors to account for non-uniform filter area usage in large-scale filter housings. This understanding proved critical to the final equipment design and depth filtration step definition, resulting in robust process performance at manufacturing scale.

Biological Products↗