A subtherapeutic international normalized ratio despite increasing doses of warfarin: could this be malabsorption?

OBJECTIVE: To describe a case of warfarin resistance apparently caused by malabsorption and to review the literature regarding warfarin resistance. CASE SUMMARY: A 28-year-old renal transplant patient with systemic lupus erythematosus was admitted for upper extremity thrombophlebitis. Resistance to oral warfarin was demonstrated. Potential causes were investigated. The trapezoidal rule was used to compare the area under the curve for intravenous versus oral dosing of warfarin. The usual bioavailability of warfarin should be 100%. In this patient, warfarin bioavailability after oral dosing was 1.5%. Three potential causes, malabsorption (FF), enzymatic degradation (FG), and first-pass extraction in the portal circulation (FH), are discussed. CONCLUSION: This case demonstrates resistance to warfarin presumably caused by malabsorption.

Audiological correlates of speech understanding deficits in elderly listeners with mild-to-moderate hearing loss. III. Factor representation.

OBJECTIVE: The objective of the study was to determine the major factors that underlie auditory/audiological performance measures in an elderly population, with particular emphasis on finding those factors responsible for speech understanding under specific conditions of interference. DESIGN: Audiological status and auditory performance of a group of elderly (60- to 81-yr-old) and normal-hearing young (18- to 30-yr-old) individuals was determined through a test battery. When present, the hearing loss of elderly subjects was symmetrical in the two ears and, at most, moderate. The battery included tests of speech intelligibility on the word and sentence levels, with and without the presence of interfering speech. In addition to pure-tone and speech reception thresholds, perception of spectrally or temporally distorted speech as well as auditory resolution of frequency, time, and space were tested. Two tests received special consideration: the Speech Perception In Noise Test and the Modified Rhyme Reverberation Test. Taking the overall results as well as various subsets of the results, principal component analyses were conducted to identify major factors underlying auditory performance. RESULTS: The factors extracted by the principal component analyses present a portrayal of the auditory performance profile in which effects of interference, high-frequency hearing, and basic auditory function play a major role. Interference factors include general susceptibility to noise as well as segregation of concurrent speech sounds on the basis of temporal dissimilarities and spatial separation. Comparison of factors extracted from various subsets of tests indicate that factors underlying the decline of the "cocktail party effect" in the elderly are addressed mostly by tests specifically designed to assess speech understanding in spatially distributed babble or in a reverberant environment. CONCLUSIONS: Factor analysis of test measures obtained from a group of elderly individuals with normal hearing or mild-to-moderate hearing loss led to two main findings. First, it portrayed hearing loss as a component of different factors rather than as a factor on its own. Second, the independence of measures of speech understanding in babble or reverberation from other measures suggests that such tests should become an integral part of audiological test batteries designed to assess auditory functions in aging.

Audiological correlates of speech understanding deficits in elderly listeners with mild-to-moderate hearing loss. II. Correlation analysis.

OBJECTIVE: The study was conducted to determine the relationship between measures of auditory performance in elderly individuals. Specifically, its goal was to uncover a set of measures correlated with the set of measures of speech understanding under specific conditions of interference to gain a better understanding of decline of the "cocktail party effect" in aging. DESIGN: Audiological status and auditory performance of a group of elderly (60- to 81-yr-old) individuals were determined through a test battery. When present, the hearing loss of elderly subjects was symmetrical in the two ears and, at most, moderate. The battery included tests of speech intelligibility on the word and sentence levels, with and without the presence of interfering speech. In addition pure-tone and speech reception thresholds, perception of spectrally or temporally distorted speech and auditory resolution of frequency, time, and space were tested. Two tests received special consideration: the Speech Perception In Noise Test and the Modified Rhyme Reverberation Test. RESULTS: Results indicated that, despite the nearly normal hearing levels that characterized much of the subject group, auditory sensitivity measures showed persistent correlation to all other measures, with the exception of auditory resolution regarding frequency, time, and space. As a set, sensitivity measures accounted for more than 85% of the variance. When auditory sensitivity was controlled for, other factors underlying speech processing in the presence of interfering stimuli were uncovered, factors most likely related to the ability to perceptually segregate one speech signal from another. CONCLUSIONS: The findings suggest that, to determine the relationship between audiological/auditory test results of an elderly population, it is important to remove the effects of hearing loss through appropriate statistical methods.

Audiological correlates of speech understanding deficits in elderly listeners with mild-to-moderate hearing loss. I. Age and lateral asymmetry effects.

OBJECTIVE: The study was conducted to answer two questions: 1) Which auditory measures detect impairments attributable to age rather than hearing loss? 2) Among the elderly, is there a lateral asymmetry of performance? DESIGN: Audiological status and auditory performance of a group of elderly (60 to 81 yr old) and normal-hearing young (18 to 30 yr old) individuals were determined through a test battery. When present, the hearing loss of elderly subjects was symmetrical in the two ears and, at most, moderate. The battery included tests of speech intelligibility on the word and sentence levels, with and without the presence of interfering speech. In addition to pure-tone and speech reception thresholds, perception of spectrally or temporally distorted speech and auditory resolution of frequency, time, and space were tested. Two tests received special consideration: the Speech Perception In Noise Test and the Modified Rhyme Reverberation Test. RESULTS: Results indicated that 1) hearing loss was a major factor differentiating auditory performance of elderly and young individuals, and 2) genuine age-related deficits were found in measures assessing auditory resolution and the ability to utilize spatial, temporal, and/or linguistic context information to perceptually separate a speech target from surrounding speech noise. Furthermore, the elderly group exhibited a right-ear advantage, caused by left-ear deficits, in tests measuring central auditory processing and a slight left-ear advantage in tests measuring peripheral auditory resolution. CONCLUSIONS: The findings suggest that, after controlling for the effect of hearing loss, there are a number of test measures in which performance of elderly and young listeners differs. Regarding lateral asymmetry, a disproportionate decline in auditory processing in the left ear of elderly individuals has been demonstrated. The major clinical conclusion is that, when testing an elderly group's performance regarding any given auditory function, the influence of pure-tone threshold elevations, no matter how mild, cannot be disregarded.

In defense of the right and left audiograms: a reply to Coren (1989) and Coren and Hakstian (1990)

Coren (1989) noticed that the various air-conduction pure-tone thresholds obtained from one ear of an individual in quiet tend to display a high correlation. In addition, Coren and Hakstian (1990) reported a consistently high correlation between pure-tone thresholds in the two ears of the same individual. On the basis of these observations, these authors proposed that pure-tone thresholds measured at audiometric frequencies in one ear, and those measured in both ears of an individual, be collapsed into a single average threshold value. The present paper disputes the usefulness and the appropriateness of such a proposal.