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PubMed1989

Anatomy of a flash. 1. Two-peak masking and a temporal filling-in.

A modified paradigm of Crawford masking was used to link masking to brightness fluctuation, as distinct from flash brightness. Thresholds were measured for a 10 ms incremental pulse (the 'probe') presented before, during, or after a 500 ms pulse (the 'flash'). Both pulses were spatially coextensive with the background field, thus the criterion for probe detection was purely temporal. The flash occurred either in the tested eye, the opposite eye, or in both eyes. In all conditions, masking was strongly bimodal: thresholds peaked near flash onset and flash offset. The flash was perceived as a unitary event. Bimodal masking is attributed to cortical on-and off-effects, as (i) dichoptic masking was strong and (ii) the same incremental probe was masked by either incremental or decremental flashes. Strikingly, monocular probe thresholds were about equally elevated by binocular as by monocular flashes, although the binocular flashes were brighter. Therefore, some monocular features can be preserved in the larger net binocular response. A general conclusion is that masking depends on the same transient neural responses that bring about a brightness fluctuation, whereas the appearance of the flash as a single event, a unitary change of brightness, depends on a different mechanism, perhaps a sustained response that performs a temporal filling-in.

Attention↗
PubMed2001

The flash-lag phenomenon: object motion and eye movements.

An object flashed briefly in a given location, the moment another moving object arrives in the same location, is perceived by observers as lagging behind the moving object (flash-lag effect). Does the flash-lag effect occur if the retinal image of the moving object is rendered stationary by smooth pursuit of the moving object? Does the flash-lag effect occur if the retinal image of a stationary object is caused to move by smooth-pursuit eye movements? A disk was briefly flashed in the center of a moving ring such that the ring center was completely 'filled' by the disk. In this display, observers perceived the flashed disk to lag such that it appeared only to partially 'fill' the ring center. The 'unfilled' portion (perceived void) of the moving ring was seen in the color of the background. With smooth pursuit of the ring, the flash-lag effect was eliminated, and observers saw the flashed disk centered on the moving ring. A strong flash-lag effect was observed when observers smoothly pursued a moving point target past a continuously visible stationary ring. Once again, the flashed disk appeared to only partially fill the center of the continuously visible stationary ring, yielding a vivid 'perceived void'. These results are discussed in terms of neural delays and their compensation.

Eye Movements↗
PubMedDate not supplied

Incremental flip angle snapshot FLASH MRI of hepatic lesions: improvement of signal-to-noise and contrast.

Incremental flip angle (IFA) snapshot fast low angle shot (FLASH) is a new modification of inversion recovery snapshot FLASH MR imaging. The method changes the flip angle incrementally from low to high during data acquisition and was applied in the evaluation of 16 focal hepatic lesions in 10 patients. Sequence comparisons were performed with a fixed flip angle inversion recovery snapshot FLASH sequence (standard), a T1- and T2-weighted spin-echo (SE) sequence, and a T1-weighted breath-hold FLASH sequence. Whereas snapshot FLASH images in both pulse sequences were free from physiological motion artifacts, SE and FLASH images showed respiratory artifacts in some patients. Quantitative analysis of IFA snapshot FLASH images at low hepatic and low lesion signal revealed both superior lesion-liver signal-difference-to-noise ratio (SD/N) and superior contrast compared with standard snapshot FLASH without additional artifacts. Unless motion artifacts were evident, SE and FLASH images showed a higher anatomic resolution but lower SD/N and lower contrast than IFA snapshot images. Because of its superior SD/N and contrast, IFA snapshot FLASH will likely widen the application of fast MR imaging techniques.

Humans↗
PubMed2001

Time course of the flash response of dark- and light-adapted human rod photoreceptors derived from the electroretinogram.

1. The a-wave of the electroretinogram was recorded from human subjects with normal vision, using a corneal electrode and ganzfeld stimulation. We applied the paired-flash technique, in which an intense 'probe' flash was delivered at different times after a 'test' flash. The amplitude of the probe-flash response provided a measure of the circulating current remaining at the appropriate time after the test flash. 2. We extended previous methods by measuring not at a fixed time, but at a range of times after the probe flash, and then calculating the ratio of the 'test-plus-probe' response to the 'probe-alone' response, as a function of time. 3. Under dark-adapted conditions the rod response derived by the paired-flash technique (in response to a relatively dim test flash) peaked at ca 120 ms, with a fractional sensitivity at the peak of ca 0.1 Td(-1) s(-1). 4. As reported previously, background illumination reduced the maximal response, reflecting a reduction in rod circulating current. In addition, it shortened the time to peak (to ca 70 ms at an intensity of 170 Td), and reduced the flash sensitivity measured at the peak. The flash sensitivity declined approximately according to Weber's Law, with a 10-fold reduction occurring at an intensity of 100-200 Td. We could not reliably measure responses at significantly higher background intensities because the circulating current became so small. 5. In order to investigate the phototransduction process after correction for response compression, we expressed the derived response as a fraction of the maximal response that could be elicited in the presence of the background. The earliest rising phase of this 'fractional response per unit intensity' was little affected by background illumination, suggesting that the amplification constant of transduction was unaltered by light adaptation.

Adaptation, Ocular↗
PubMedDate not supplied

Dependence of the flash-induced oxygen evolution pattern on the chemically and far red light-modulated redox condition in cyanobacterial photosynthetic electron transport.

Flash-induced photosynthetic oxygen evolution was measured in cells and thylakoid preparations from the coccoid cyanobacteria Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7942 and from the filamentous cyanobacterium Oscillatoria chalybea. The resulting characteristic flash patterns from these cyanobacteria can be chemically altered by addition of exogenously added substances like CCCP, DCPiP and inorganic salts. Potassium chloride, manganese sulfate and calcium chloride affected the sequences by specific increases in the flash yield and/or effects on the transition parameters. Chloride appeared to exert the strongest stimulatory effect on the oxygen yield. In comparison to chloride, both manganese and calcium did not significantly stimulate the flash amplitudes as such, but improved the functioning of the oxygen evolving complex by decreasing the miss parameter alpha. Particular effects were observed with respect to the time constants of the relaxation kinetics of the first two flash signals Y1/Y2 of the cyanobacterial patterns. In the presence of the investigated chemicals the amplitudes of the first two flash signals (Y2 in particular) were increased and the relaxation kinetics were enhanced so that the time constant became about identical to the conditions of steady state oxygen flash amplitudes. The results provide further evidence against a possible participation of either PS I or respiratory processes to Y1/Y2 of cyanobacterial flash patterns. Dramatic effects were observed when protoplasts from Oscillatoria chalybea or cells from Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7942 were exposed to weak far red background illumination. Under these conditions, Y2 (and to a smaller extent Y1) of otherwise unchanged flash sequences were specifically modified. Y2 was substantially increased and again the relaxation kinetics were accelerated making the signal indistinguishable from a Y(SS) signal. From the mathematical fit of the sequences we conclude that S2 contributes to 10-20% of the S-state distribution (in comparison to 0% in the control). Thus, far red background illumination might represent a valuable means for photosynthetic investigations where high amounts of S2 are required like e. g. EPR measurements. In such experiments the corresponding EPR signals appeared substantially enhanced following far red preillumination (Ahrling and Bader, unpublished observations). Our results clearly show that the 'controversial results' from parts of the literature suggesting the participation of different mechanisms (net oxygen evolution, inhibited uptake processes etc.) are not required to explain the flash-induced oxygen evolution in cyanobacteria: the seemingly 'incompatible' conditions and conformations can be perfectly interconverted by different modulation techniques (chemicals, far red) of the respective redox condition within the water oxidation complex of photosynthesis.

2,4-Dinitrophenol↗
PubMed1994

Visual readaptation after flash exposure under scotopic conditions. A study using optokinetic nystagmus as an indicator of visual perception.

The purpose of the present study was to establish a method for objective measurements of visual readaptation after flash exposures and to define a model for measurements. Influences of target direction, luminance and velocity on optokinetic nystagmus (OKN) were investigated under scotopic conditions. Visual readaptation was measured using OKN as an indicator of visual perception after exposure to a flash. The interval between the triggering of the flash and the reoccurrence of OKN was defined as the visual readaptation time (RAT). A Goldmann perimeter hemisphere was used for flash stimulation. A horizontally moving vertical grating projected inside the hemisphere was used as the OKN stimulus. Eye movements were recorded by DC electrooculography (EOG). The dependence of RAT on the dose of the flash, the wavelength of the flash and the luminance of the OKN target were investigated. The precision of the measurement method was studied. This includes the analysis of the variance due to the experimental occasions, the repeated exposures, the sexes of the subjects, the methods for recognition of OKN and the ways of visual adaptation before measurements. The contributions of retinal receptor and the neural activity to RAT were investigated by electroretinography (ERG). The influences of target direction and luminance on binocular motion perception and OKN as well as monocular OKN were examined at various target velocities. The dependence of the frequency and amplitude of eye jerks during monocular OKN on target luminance and velocity were also examined. It was found that RAT increases with increasing doses of the flash or decreasing luminance of the grating. RAT is most extended after flashes near 520 nm. RAT does not differ between experimental occasions, between a manual and a semi-automatic method for recognition of OKN, between the sexes and between goggle adaptation and ordinary dark adaptation. There is a reduction of RAT due to repeated flash exposures. The data collected indicate that a well-defined model is crucial for measurements of RAT. The measurement of ERG showed that RAT is mediated by both retinal receptor and the neural activities. The receptor component depends on the wavelength of the flash while the neural component is wavelength-independent. Moreover, it was found that motion perception and OKN gain does not differ between right and left target directions. For a given target velocity, motion perception and OKN gain under both binocular and monocular viewing conditions increase with increasing luminance of the target with an exponential decay. The maximum OKN gain decreases as target velocity increases.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Ocular↗
PubMed2005

Hot flashes: behavioral treatments, mechanisms, and relation to sleep.

Hot flashes are the most common symptom of the climacteric and occur in about 75% of perimenopausal and postmenopausal women in Western societies. Although hot flashes accompany the withdrawal of estrogen at menopause, the decline in estrogen levels is not sufficient to explain their occurrence. Elevated sympathetic activation acting through central alpha(2)-adrenergic receptors contributes to the initiation of hot flashes, possibly by narrowing the thermoneutral zone in symptomatic women. Hot flashes are then triggered by small elevations in core body temperature acting within this narrowed zone. A relaxation-based method, paced respiration, has been shown in 3 controlled investigations to significantly reduce objectively measured hot flash occurrence by about 50% with no adverse effects. In 6 studies of physical exercise, however, investigators did not find positive effects on hot flashes, possibly because exercise raises core body temperature, thereby triggering hot flashes. Although many epidemiologic studies have found increased reports of sleep disturbance during the menopausal transition, recent laboratory investigations have not found this effect, nor have they found that hot flashes produce disturbed sleep. Therefore, sleep complaints in women at midlife should not routinely be attributed to hot flashes or to menopause.

Behavior Therapy↗
PubMed2006

Cigarette smoking, estrogen levels, and hot flashes in midlife women.

OBJECTIVE: The aims of this study were to examine the association of smoking with the occurrence, frequency, and severity of hot flashes and to determine whether the mechanism by which active cigarette smoking increases the risk of hot flashes is by lowering estradiol and estrone levels. METHODS: A case-control study was conducted among women aged 45-54 years to examine risk factors for hot flashes. Cases were women who reported ever experiencing hot flashes (n = 353). Controls were women who reported never experiencing hot flashes (n = 258). Each participant completed a questionnaire and provided a blood sample that was used to measure estradiol and estrone levels. RESULTS: The results showed that both current and ever smokers had higher odds than never smokers of experiencing any and more severe hot flashes. Further, significant positive associations were observed between frequency and duration of smoking and the experiencing of any and more severe hot flashes. Smoking was not associated with estradiol or estrone levels in univariate analyses. In addition, the odds ratios for the associations between the cigarette smoking variables and hot flashes did not change when the hormone variables were added to the model. CONCLUSIONS: These findings indicate that smoking is associated with the occurrence of any and more severe hot flashes, independent of estrogen levels.

Baltimore↗
PubMed2002

Complementary/alternative therapies for reducing hot flashes in prostate cancer patients: reevaluating the existing indirect data from studies of breast cancer and postmenopausal women.

Vasomotor hot flashes are a common problem in women who are postmenopausal or receiving antiestrogen treatment for breast cancer. Hot flashes are also a common problem after orchiectomy/luteinizing hormone-releasing hormone therapy, occurring generally in 50% to 66% of these men. Prescribed treatments for hot flashes for men on hormonal ablation treatment for prostate cancer are well documented. These conventional agents have shown good results, but their long-term efficacy, safety, and cost are still questioned. Therefore, the search for other viable agents, including nontraditional treatments, continues. Complementary/alternative treatments to alleviate hot flashes in women have generated an enormous amount of interest. However, these options have received little attention in men with hot flashes. Research with vitamin E, soy, black cohosh, red clover, and numerous other alternative treatments in women may provide some indirect but valuable insight on their potential effectiveness in men. Many of these alternatives have been a disappointment in recent randomized trials of women, and it is likely that there will be similar results with men. However, numerous supplements have yet to be tested in a clinical trial against a placebo, and clinicians should become aware of this ever-increasing list. Patients should be made aware of the primary importance of lifestyle interventions that could partially affect hot flashes and immediately affect overall health, especially during the period of androgen suppression, when it is not uncommon to observe accelerated weight changes and insulin insensitivity. Otherwise, recent research with older and newer conventional agents, such as antidepressants or estrogen/progesterone, should be emphasized at this time for moderate-to-severe hot flashes that profoundly affect daily activities and/or sleep. Antidepressant supplements (St. John's wort) or acupuncture could also be an attractive option in future investigations. Low-dose estrogen seems particularly attractive, because it is inexpensive and may simultaneously reduce hot flashes and the risk of osteoporosis in men receiving long-term androgen suppression therapy; however, the potential for cardiovascular complications must be further investigated. Ultimately, adequate research (vs placebo) should determine the fate of the alternative supplements proposed for hot flash reduction.

Acupuncture↗
PubMed2003

Menopausal hot flash and calciotonin gene-related peptide; effect of Keishi-bukuryo-gan, a kampo medicine, related to plasma calciotonin gene-related peptide level.

OBJECTIVES: The purpose of this study is to investigate relationship of menopausal hot flash and calcitonin gene-related peptide (CGRP). Furthermore, this study evaluated the effect of the Japanese herbal (kampo) medicine Keishi-bukuryo-gan from the aspect of CGRP regulation. METHODS: Plasma CGRP and vasoactive intestinal peptide (VIP) levels were measured during hot flash and CGRP reactivity was studied by cold load test in subjects with/without hot flashes. The effect of Keishi-bukuryo-gan was assessed in comparison with plasma CGRP level. RESULTS: Only plasma CGRP but not VIP significantly elevated at the occurrence of hot flash (P=0.002). Stress by cold load significantly enhanced the over-secretion of CGRP in subjects with flash compared with those without flash (P=0.003) 3 min after the load. Keishi-bukuryo-gan decreased plasma CGRP level in subjects with hot flash. CONCLUSIONS: CGRP but not VIP was mainly related to the occurrence of hot flash. Keishi-bukuryo-gan, Japanese herbal medicine, improves hot flash possibly affecting plasma CGRP level.

Calcitonin Gene-Related Peptide↗
PubMed2004

Pilot evaluation of black cohosh for the treatment of hot flashes in women.

BACKGROUND: Hot flashes cause significant morbidity in postmenopausal women, including women with breast cancer. We undertook a pilot study to estimate the effectiveness of black cohosh to reduce hot flashes. METHODS: Women who reported significant hot flashes (> or = 14 per week) were enrolled. Black cohosh was given in the form of the commercial product Remifemin. The first week was a no-treatment baseline period, and therapy was given for the subsequent 4 weeks. Hot flash data were collected by daily questionnaires during baseline and treatment weeks. Adverse effects were recorded. RESULTS: Twenty-one women completed the study. Their mean age was 56 years (range, 38-80). Thirteen patients had a history of breast cancer. Six patients were taking tamoxifen or raloxifene. Patients reported an average of 8.3 hot flashes per day during the baseline week. The reduction in mean daily hot flash frequency was 50% (95% CI, 34%-65%), while weekly hot flash scores were reduced 56% (95% CI, 40%-71%) at completion of the study. Overall, patients reported less trouble with sleeping, less fatigue, and less abnormal sweating. No patients stopped therapy because of adverse effects. CONCLUSIONS: Black cohosh appeared to reduce hot flashes and had a low toxicity. The efficacy found in this trial seems to be more than would be expected by a placebo effect (20%-30% hot flash reduction in previous trials). These results suggest that further evaluation of this black cohosh preparation with a phase III randomized trial is indicated.

Adolescent↗
PubMed2005

Pilot evaluation of citalopram for the treatment of hot flashes in women with inadequate benefit from venlafaxine.

BACKGROUND: While newer antidepressants, such as venlafaxine and paroxetine, substantially decrease hot flashes, there is no published information with regards to whether a different antidepressant will be effective when one antidepressant does not adequately relieve hot flashes. OBJECTIVE: The objective of this trial was to provide pilot information with regards to whether citalopram would effectively reduce hot flashes in patients who did not receive adequate enough hot flash reduction with venlafaxine. DESIGN: This was a prospective pilot trial. MEASUREMENTS: Validated patient-completed hot flash diary questionnaires were utilized for measuring hot flashes. SUBJECTS: Thirty patients were recruited to this trial, 22 of whom were fully evaluable. RESULTS: Compared to a baseline week, hot flash scores were reduced by 53% 4 weeks later. The citalopram appeared to be well tolerated with many quality-of-life and potential toxicity symptoms much improved compared to the baseline week. At the end of the 4-week treatment, 19 patients (63% of patients entering the study and 86% of the patient completing the study treatment) chose to continue to use citalopram. CONCLUSION: This pilot information supports the hypothesis that citalopram will reduce hot flashes in patients with inadequate hot flash relief while taking venlafaxine.

Adult↗
PubMed2006

Pilot evaluation of bupropion for the treatment of hot flashes.

Bupropion is commonly used in the treatment of nicotine dependence and depression, and in most people, does not cause sexual dysfunction, weight gain, or sedation. Given its attractive side effect profile, the efficacy of other newer antidepressants against hot flashes and anecdotal observations of resolution of hot flashes in some patients taking bupropion for nicotine dependence, it was decided to explore its clinical activity as a hot flash remedy in a pilot study. Between January 1999 and October 2004, 21 patients (7 men and 14 women) were enrolled in the study. Self-completed daily hot flash diaries were used to document the frequency and severity of hot flashes at baseline (week 1) and during the treatment period (weeks 2 through 5). Participants received bupropion 150 mg every morning for the first 3 days and then 150 mg twice per day for a total of 4 weeks. One woman did not provide any hot flash information and was excluded from the analysis. Five women could not complete the study because of side effects. The study did not show a reduction in hot flash frequency and/or severity significantly higher than what would be expected with a placebo. Even though the sample size was small, these results are consistent with bupropion's mechanism of action (norepinephrine reuptake inhibition without serotonergic effects) and what it is now hypothesized about the pathophysiology of hot flashes (increased noradrenergic activity and decreased serotonergic activity). These data suggest that bupropion should not be further investigated as a remedy for hot flashes.

Adolescent↗
PubMed2005

Stellate ganglion blockade provides relief from menopausal hot flashes: a case report series.

OBJECTIVE: To investigate whether standard C6 stellate ganglion blockade (SGB) might provide relief from hot flashes associated with menopause. METHODS: Six women were referred for severe menopausal hot flashes and elected to undergo standard SGB (5 ml 0.375% Marcaine, Abbott Labs, Abbott Park, IL) to evaluate a novel intervention for hot flash relief. Hot flashes were assessed by self-reporting before and after stellate ganglion block. RESULTS: Initial SGB (SGB1) was successful in all 6 subjects, as evidenced by a positive Horner's syndrome and anhydrosis. Successful SGB caused complete alleviation of hot flashes for times ranging from 2 to 5 weeks. Patients returned for follow-up SGB after mild hot flashes returned. A second SGB produced additional asymptomatic periods of relief ranging from 4 to 18 weeks. In each case, repeated block provided hot flash relief equal to or greater than that of the initial block. Two patients who submitted for a third SGB reported 15 and 48 weeks of relief. CONCLUSION: Successful SGB appears to be related to relief of hot flashes. Repeat SGB results in efficacious multiple week relief of severe hot flashes associated with menopause.

Anesthesia, Local↗
PubMedDate not supplied

Menopausal Vasomotor Symptoms (MVS) survey for assessment of hot flashes.

OBJECTIVES: During the menopause, 65%-80% of women experience hot flashes. Hot flashes can also occur after hysterectomy and may be experienced during cancer therapy. A very limited assessment of hot flashes is provided by currently available menopausal instruments. This study was performed to evaluate a new Menopausal Vasomotor Symptoms (MVS) survey as an instrument for a comprehensive and subjective assessment of hot flashes. METHODS: The MVS survey was designed to assess multiple dimensions of hot flashes and to be simple and easy to administer. Hot flashes and associated conditions were addressed with 39 closed-ended questions. Sixty-one qualified women, 40-58 years old, from the Dallas, Fort Worth Metroplex area were enrolled. Women experiencing hot flashes took the survey at baseline and then 14 days, 2 months, and 6 months later. Factor analysis was performed. Face and content validity, internal consistency, test-retest reliability, and sensitivity to changes were evaluated. RESULTS: Fifty-two women (85.2%) completed all study sessions. The MVS survey was found to have good face and content validity and good internal consistency (rhoKR = 0.87). Spearman rank-order correlation coefficients at the 14-day retest varied from 0.58 to 1.00. As a result of these analyses, the MVS survey was further refined. CONCLUSIONS: The MVS survey was found to be comprehensive, simple, valid, reliable, sensitive, and a convenient instrument for subjective assessment of various characteristics of hot flashes. The MVS survey may serve as a valuable clinical and research tool for measurement of hot flashes.

Adult↗
PubMedDate not supplied

Effects of REM sleep and ambient temperature on hot flash-induced sleep disturbance.

OBJECTIVE: To determine whether hot flashes produce sleep disturbance in postmenopausal women. DESIGN: This study was performed in a university medical center laboratory with 18 postmenopausal women with hot flashes, six with no hot flashes, and 12 cycling women, all healthy and medication free. Polysomnography, skin and rectal temperatures, and skin conductance to detect hot flashes were recorded for four nights. Nights 2, 3, and 4 were run at 30 degrees C, 23 degrees C, and 18 degrees C in randomized order. RESULTS: During the first half of the night, the women with hot flashes had significantly more arousals and awakenings than the other two groups and the 18 degrees C ambient temperature significantly reduced the number of hot flashes, from 2.2 +/- 0.4 to 1.5 +/- 0.4. These effects did not occur in the second half of the night. In the first half of the night, most hot flashes preceded arousals and awakenings. In the second half, this pattern was reversed. CONCLUSIONS: In the second half of the night, rapid eye movement sleep suppresses hot flashes and associated arousals and awakenings. This may explain previous discrepancies between self-reported and laboratory-reported data in postmenopausal women with hot flashes.

Cold Temperature↗
PubMedDate not supplied

Hot flashes are associated with increased ambulatory systolic blood pressure.

OBJECTIVE: To determine the association between ambulatory blood pressure (BP) and hot flash experience. DESIGN: The participants in the study were 154 women (mean age=46 years, range=18-65 years), who were evaluated as part of a cross-sectional study on ethnicity, socioeconomic status, and diurnal BP patterns. Participants could be either normotensive or mildly hypertensive. Participants wore an ambulatory BP monitor for 24 hours and recorded their awake and sleep times. Hot flashes were assessed using an everyday complaint questionnaire that embeds symptoms associated with menopause into a list of everyday complaints. RESULTS: Thirty-three percent of participants reported having had hot flashes during the 2 weeks before they completed the questionnaire. Compared with women who did not report hot flashes, mean awake and sleep systolic BP values were significantly higher (P<0.004 and P=0.007, respectively) in women who reported having had hot flashes. Hot flashes continued to independently predict average awake and sleep systolic BP (both P=0.03) after controlling for age, race/ethnicity, body mass index, and menopausal status. Hot flashes were not associated with diastolic BP or nocturnal dipping of BP. CONCLUSIONS: Hot flashes are associated with increased awake and sleep systolic BP independent of menopausal status. Further investigation is warranted to elucidate the mechanisms by which hot flashes are associated with BP.

Adolescent↗
PubMed2005

Identifying methodologies in the assessment of treatment effects on the repeated occurrences of hot flashes in postmenopausal women.

BACKGROUND: Two methods that are commonly used in most clinical trials for evaluating the effect of treatment on hot flashes are frequency only and severity score methods. However, in these crude methods, composite recurrent hot flash data on a patient are reduced to a one-dimensional summary measure, an approach which may not be optimal. In addition, the duration of a hot flash event provides additional information, which is not accounted for in the two methods mentioned above. PURPOSE: We propose two new methods in the analysis of hot flash data in this paper. METHODS: The first method utilizes a generalization of the continuation ratio model to model the severity of a hot flash event. The model accounts for individual random effects and dependence of recurrent events within an individual. The other method that accounts for the duration of a hot flash event is a 3-Dimensional (3D) score method, which incorporates hot flash information on frequency, severity, and duration. RESULTS: Simulation studies were conducted to evaluate the properties of our proposed methods. The results indicate that our proposed generalized continuation ratio model has appreciably high power in detecting small treatment effects on severity compared with the two commonly used methods. The proposed 3D score, on the other hand, is sensitive in detecting treatment effects on both frequency and duration, but has low power in detecting treatment effects on severity alone. CONCLUSIONS: Our proposed generalized continuation ratio model approach provides a valuable and powerful alternative to the two commonly used methods in the analysis of treatment effects on hot flash severity. Our proposed 3D score method incorporates the additional information hot flash duration provides, and is another analysis option for the practitioners to employ.

Analysis of Variance↗