3-D-Printed Models for Temporal Bone Training: A Validity Study.

OBJECTIVE: 3-D printing offers convenient and low-cost mastoidectomy training; nonetheless, training benefits using 3-D-printed temporal bones remain largely unexplored. In this study, we have collected validity evidence for a low-cost, 3-D-printed temporal bone for mastoidectomy training and established a credible pass/fail score for performance on the model. STUDY DESIGN: A prospective educational study gathering validity evidence using Messick's validity framework. SETTING: Seven Danish otorhinolaryngology training institutions. PARTICIPANTS: Eighteen otorhinolaryngology residents (novices) and 11 experienced otosurgeons (experts). INTERVENTION: Residents and experienced otosurgeons each performed two to three anatomical mastoidectomies on a low-cost, 3-D-printed temporal bone model produced in-house. After drilling, mastoidectomy performances were rated by three blinded experts using a 25-item modified Welling scale (WS). MAIN OUTCOME MEASURE: Validity evidence using Messick's framework including reliability assessment applying both classical test theory and Generalizability theory. RESULTS: Novices achieved a mean score of 13.9 points; experienced otosurgeons achieved 23.2 points. Using the contrasting groups method, we established a 21/25-point pass/fail level. The Generalizability coefficient was 0.91, and 75% of the score variance was attributable to participant performance, indicating a high level of assessment reliability. Subsequent D studies revealed that two raters rating one performance or one rater rating two performances were sufficiently reliable for high-stakes assessment. CONCLUSION: Validity evidence supports using a low-cost, 3-D-printed model for mastoidectomy training. The model can be printed in-house using consumer-grade 3-D printers and serves as an additional training tool in the temporal bone curriculum. For competency-based training, we established a cut-off score of 21 of 25 WS points using the contrasting groups method.

Occupational noise exposure, psychosocial working conditions and the risk of tinnitus.

PURPOSE: The purpose of this study was to evaluate the influence of occupational noise (current and cumulative doses) and psychosocial work factors (psychological demands and decision latitude) on tinnitus occurrence among workers, using objective and non-self-reported exposure measures to prevent reporting bias. METHODS: In a cross-sectional study, we analyzed data from a Danish survey from 2009 to 2010 that included 534 workers from children day care units and 10 manufacturing trades. Associations between risk factors (current noise exposure, cumulative noise exposure and psychosocial working conditions) and tinnitus were analyzed with logistic regression. RESULTS: We found no statistically significant associations between either current [OR 0.95 (95% CI 0.89; 1.01)] or cumulative [OR 0.93 (95% CI 0.81; 1.06)] occupational noise exposure and tinnitus. Likewise, results for psychosocial working conditions showed no statistically significant association between work place decision latitude [OR 1.06 (95% CI 0.94; 1.13)] or psychological demands [OR 1.07 (95% CI 0.90; 1.26)] and tinnitus. CONCLUSIONS: Our results suggest that current Danish occupational noise levels (in combination with relevant noise protection) are not associated with tinnitus. Also, results indicated that the psychosocial working conditions we observed in this cohort of mainly industrial workers were not associated with tinnitus. Therefore, psychosocial working conditions comparable to those observed in this study are probably not relevant to take into account in the evaluation of workers presenting with tinnitus.

Atherogenic risk factors and hearing thresholds.

The objective of this study was to evaluate the influence of atherogenic risk factors on hearing thresholds. In a cross-sectional study we analyzed data from a Danish survey in 2009-2010 on physical and psychological working conditions. The study included 576 white- and blue-collar workers from children's day care units, financial services and 10 manufacturing trades. Associations between atherogenic risk factors (blood lipids, glycosylated hemoglobin, smoking habits, body mass index (BMI), and ambulatory blood pressure) and hearing thresholds were analyzed using multiple linear regression models. Adjusted results suggested associations between smoking, high BMI and triglyceride level and low high-density lipoprotein level and increased low-frequency hearing thresholds (average of pure-tone hearing thresholds at 0.25, 0.5 and 1 kHz). Furthermore, an increasing load of atherogenic risk factors seemed associated with increased low-frequency hearing thresholds, but only at a borderline level of statistical significance. Associations were generally strongest with hearing levels of the worst hearing ear. We found no statistically significant associations between atherogenic risk factors and high-frequency hearing thresholds (average of pure-tone hearing thresholds at 4, 6 and 8 kHz).

Recent and long-term occupational noise exposure and salivary cortisol level.

Environmental and occupational noise exposure have been related to increased risk of cardiovascular disease, hypothetically mediated by stress-activation of the hypothalamic-pituitary-adrenal (HPA) axis. The objective of this study was to investigate the relation between recent and long-term occupational noise exposure and cortisol level measured off work to assess a possible sustained HPA-axis effect. We included 501 industrial, finance, and service workers who were followed for 24h during work, leisure, and sleep. Ambient occupational noise exposure levels were recorded every 5s by personal dosimeters and we calculated the full-shift LAEq value and estimated duration and cumulative exposure based on their work histories since 1980. For 332 workers who kept a log-book on the use of hearing protection devices (HPD), we subtracted 10 dB from every noise recording obtained during HPD use and estimated the noise level at the ear. Salivary cortisol concentration was measured at 20.00 h, the following day at awakening, and 30 min after awakening on average 5, 14 and 14.5h after finishing work. The mean ambient noise exposure level was 79.9 dB(A) [range: 55.0-98.9] and the mean estimated level at the ear 77.7 dB(A) [range: 55.0-94.2]. In linear and mixed regression models that adjusted for age, sex, current smoking, heavy alcohol consumption, personal income, BMI, leisure-time noise exposure level, time since occupational noise exposure ceased, awakening time, and time of saliva sampling, we observed no statistically significant exposure response relation between recent, or long-term ambient occupational noise exposure level and any cortisol parameter off work. This was neither the case for recent noise level at the ear. To conclude, neither recent nor long-term occupational noise exposure levels were associated with increased cortisol level off work. Thus, our results do not indicate that a sustained activation of the HPA axis, as measured by cortisol, is involved in the causal pathway between occupational noise exposure and cardiovascular disease.