Optimal design of studies of influenza transmission in households. II: comparison between cohort and case-ascertained studies.

Both case-ascertained household studies, in which households are recruited after an 'index case' is identified, and household cohort studies, where a household is enrolled before the start of the epidemic, may be used to test and estimate the protective effect of interventions used to prevent influenza transmission. A simulation approach parameterized with empirical data from household studies was used to evaluate and compare the statistical power of four study designs: a cohort study with routine virological testing of household contacts of infected index case, a cohort study where only household contacts with acute respiratory illness (ARI) are sampled for virological testing, a case-ascertained study with routine virological testing of household contacts, and a case-ascertained study where only household contacts with ARI are sampled for virological testing. We found that a case-ascertained study with ARI-triggered testing would be the most powerful design while a cohort design only testing household contacts with ARI was the least powerful. Sensitivity analysis demonstrated that these conclusions varied by model parameters including the serial interval and the risk of influenza virus infection from outside the household.

Optimal design of studies of influenza transmission in households. I: case-ascertained studies.

Case-ascertained household transmission studies, in which households including an 'index case' are recruited and followed up, are invaluable to understanding the epidemiology of influenza. We used a simulation approach parameterized with data from household transmission studies to evaluate alternative study designs. We compared studies that relied on self-reported illness in household contacts vs. studies that used home visits to collect swab specimens for virological confirmation of secondary infections, allowing for the trade-off between sample size vs. intensity of follow-up given a fixed budget. For studies estimating the secondary attack proportion, 2-3 follow-up visits with specimens collected from all members regardless of illness were optimal. However, for studies comparing secondary attack proportions between two or more groups, such as controlled intervention studies, designs with reactive home visits following illness reports in contacts were most powerful, while a design with one home visit optimally timed also performed well.

Sleep continuity and architecture: associations with pain-inhibitory processes in patients with temporomandibular joint disorder.

Recent research suggests bi-directional interactions between the experience of pain and the process of sleep; pain interferes with the ability to obtain sleep, and disrupted sleep contributes to enhanced pain perception. Our group recently reported, in a controlled experimental study, that sleep fragmentation among healthy adults resulted in subsequent decrements in endogenous pain inhibition. The present report follows up that observation by extending this line of research to a sample of patients experiencing persistent pain. Patients with chronic temporomandibular joint disorder (TMD) pain were studied using polysomnography and psychophysical evaluation of pain responses. We assessed whether individual differences in sleep continuity and/or architecture were related to diffuse noxious inhibitory controls (DNIC), a measure of central nervous system pain inhibition. Among 53 TMD patients, higher sleep efficiency and longer total sleep time were positively associated with better functioning of DNIC (r=0.42-0.44, p<0.01; ps<0.05 for the multivariate analyses). These results suggest the possibility that disrupted sleep may serve as a risk factor for inadequate pain-inhibitory processing and hint that aggressive efforts to treat sleep disturbance early in the course of a pain condition might be beneficial in reducing the severity or impact of clinical pain.

Improvement in bone homeostasis following autologous chondrocyte implantation of the knee.

This retrospective review and clinical follow-up demonstrates the effectiveness of autologous chondrocyte implantation of the knee. From September 1995 to June 2001, 24 patients with average follow-up of 26.5 months were evaluated. The mean Lysholm score improved from 43.58 before surgery to 71.42 at most recent follow-up, the modified Cincinnati knee score for overall clinician evaluation improved from 2.96 to 6.92, and the mean modified Cincinnati knee score for overall patient evaluation improved from 3.21 to 6.13 at P <.05. Seventy-nine percent of patients responded that they would have the same knee surgery again and 83% rated the results of their knee surgery as good to excellent. Limited radionuclide bone scans with single photon emission computed tomography were completed in 11 of the patients to assess the physiology and homeostasis of subchondral bone adjacent to treated articular cartilage defects. A trend was identified suggesting improvement in subchondral bone scores at a mean of 29.6-months follow-up compared to preoperative bone scan assessment. There also was a trend towards greatest improvement correlating with the patients with the best clinical scores. The results of this study suggest that autologous chondrocyte implantation of the knee can be successful in improving pain and function in patients with articular cartilage defects.