Stressful life events, gender and obesity: A prospective, population-based study of adolescents in British Columbia.

OBJECTIVE: To determine whether stressful life events are related to levels of obesity in a group of ethnically diverse Canadian youth and the extent to which the relationship differs by gender. METHODS: This study of 905 adolescents (age 13-17 years) from a BC population-based cohort (BASUS) used self-reported data from Wave 5 (2011 fall) on stressful life events and socio-demographic factors and from Wave 6 (2012 spring) on weight and height. Multivariable logistic regression models conditioned on known confounders and used a cross-product term for effect modification by gender. Post-estimation analysis calculated gender-specific predicted mean probabilities of having obesity associated with greater frequency of stressful life events. RESULTS: Compared to young men reporting no stressful life events in the previous year, young men reporting one event were nearly 50% more likely to have obesity at 6-month follow-up (OR 1.47 [95% CI: 0.63, 3.41]) and those reporting multiple stressful life events were twice as likely to have obesity at 6-month follow-up (OR 2.07 [95% CI: 0.79-5.43]). Only young women reporting multiple events showed a higher likelihood of having obesity at the end of the study (OR 1.32 [95% CI: 0.41-4.18]) than their counterparts reporting no life events. CONCLUSIONS: Results suggest that the frequency of major life events may be an important social stressor associated with obesity in adolescents, particularly for young men. However, findings should be replicated in larger samples using measured anthropometry to inform future obesity prevention strategies.

A randomized controlled trial of tibial component migration with kinematic alignment using patient-specific instrumentation versus mechanical alignment using computer-assisted surgery in total knee arthroplasty.

AIMS: Patient-specific instrumentation of total knee arthroplasty (TKA) is a technique permitting the targeting of individual kinematic alignment, but deviation from a neutral mechanical axis may have implications on implant fixation and therefore survivorship. The primary objective of this randomized controlled study was to compare the fixation of tibial components implanted with patient-specific instrumentation targeting kinematic alignment (KA+PSI) versus components placed using computer-assisted surgery targeting neutral mechanical alignment (MA+CAS). Tibial component migration measured by radiostereometric analysis was the primary outcome measure (compared longitudinally between groups and to published acceptable thresholds). Secondary outcome measures were inducible displacement after one year and patient-reported outcome measures (PROMS) over two years. The secondary objective was to assess the relationship between alignment and both tibial component migration and inducible displacement. PATIENTS AND METHODS: A total of 47 patients due to undergo TKA were randomized to KA+PSI (n = 24) or MA+CAS (n = 23). In the KA+PSI group, there were 16 female and eight male patients with a mean age of 64 years (sd 8). In the MA+CAS group, there were 17 female and six male patients with a mean age of 63 years (sd 7). Surgery was performed using cemented, cruciate-retaining Triathlon total knees with patellar resurfacing, and patients were followed up for two years. The effect of alignment on tibial component migration and inducible displacement was analyzed irrespective of study group. RESULTS: There was no difference over two years in longitudinal migration of the tibial component between the KA+PSI and MA+CAS groups (reaching median maximum total point motion migration at two years of 0.40 mm for the KA+PSI group and 0.37 mm for the MA+CAS group, p = 0.82; p = 0.68 adjusted for age, sex, and body mass index (BMI) for all follow-ups). Both groups had mean migrations below acceptable thresholds. There was no difference in inducible displacement (p = 0.34) or PROMS (p = 0.61 for the Oxford Knee Score) between groups. There was no correlation between alignment and tibial component migration or alignment and inducible displacement. These findings support non-neutral alignment as a viable option with this component, with no evidence that it compromises fixation. CONCLUSION: Kinematic alignment using patient-specific instrumentation in TKA was associated with acceptable tibial component migration, indicating stable fixation. These results are supportive of future investigations of kinematic alignment. Cite this article: Bone Joint J 2019;101-B:929-940.

Predictive value of short-term migration in determining long-term stable fixation in cemented and cementless total knee arthroplasties.

AIMS: Early implant migration measured with radiostereometric analysis (RSA) has been proposed as a useful predictor of long-term fixation of tibial components in total knee arthroplasty. Evaluation of actual long-term fixation is of interest for cemented components, as well as for cementless fixation, which may offer long-term advantages once osseointegration has occurred. The objective of this study was to compare the long-term migration with one- and two-year migration to evaluate the predictive ability of short-term migration data and to compare migration and inducible displacement between cemented and cementless (porous metal monoblock) components at least ten years postoperatively. PATIENTS AND METHODS: Patients who had participated in RSA migration studies with two-year follow-up were recruited to return for a long-term follow-up, at least ten years from surgery. Two cemented tibial designs from two manufacturers and one porous metal monoblock cementless tibial design were studied. At the long-term follow-up, patients had supine RSA examinations to determine migration and loaded examinations (single leg stance) to determine inducible displacement. In total, 79 patients (54 female) returned, with mean time since surgery of 12 years (10 to 14). There were 58 cemented and 21 cementless tibial components. RESULTS: Migration at one year and two years was significantly correlated with long-term migration (p < 0.001). Median migration at the long-term follow-up was 0.6 mm (maximum total point motion; interquartile range (IQR) 0.4 to 0.9) for the cemented group and 0.6 mm (IQR 0.3 to 1.1) for the cementless group with no difference between groups (p = 0.99). Inducible displacement was significantly lower for the cementless components (p < 0.001). CONCLUSION: Long-term migration was strongly correlated with two-year migration. Although long-term migration was not different for cemented or cementless tibial components, inducible displacement at the long-term visit was significantly lower for these cementless components, suggesting superior fixation. These findings support the predictive value of short-term migration in determining long-term fixation. Cite this article: Bone Joint J 2019;101-B(7 Supple C):55-60.

The assessment of the stability of the tibial component of a novel knee arthroplasty system using radiostereometric analysis.

AIMS: The introduction of a novel design of total knee arthroplasty (TKA) must achieve outcomes at least as good as existing designs. A novel design of TKA with a reducing radius of the femoral component and a modified cam-post articulation has been released and requires assessment of the fixation to bone. Radiostereometric analysis (RSA) of the components within the first two postoperative years has been shown to be predictive of medium- to long-term fixation. The aim of this study was to assess the stability of the tibial component of this system during this period of time using RSA. PATIENTS AND METHODS: A cohort of 30 patients underwent primary, cemented TKA using the novel posterior stabilized fixed-bearing (ATTUNE) design. There was an even distribution of men and women (15:15). The mean age of the patients was 64 years (sd 8) at the time of surgery; their mean body mass index (BMI) was 35.4 kg/m 2 (sd 7.9). RSA was used to assess the stability of the tibial component at 6, 12, and 24 months compared with a six-week baseline examination. Patient-reported outcome measures were also assessed. RESULTS: The mean maximum total point motion (MTPM) of the tibial component between 12 and 24 months postoperatively was 0.08 mm (sd 0.08), which is well below the published threshold of 0.2 mm (p < 0.001). Patient-reported outcome measures consistently improved. CONCLUSION: The tibial component of this novel design of TKA showed stability between assessment 12 and 24 months postoperatively, suggesting an acceptably low risk of medium- to long-term failure due to aseptic loosening.

Stable migration of peri-apatite-coated uncemented tibial components in a multicentre study.

AIMS: Hydroxyapatite coatings for uncemented fixation in total knee arthroplasty can theoretically provide a long-lasting biological interface with the host bone. The objective of this study was to test this hypothesis with propriety hydroxyapatite, peri-apatite, coated tibial components using component migration measured with radiostereometric analysis over two years as an indicator of long-term fixation. PATIENTS AND METHODS: A total of 29 patients at two centres received uncemented PA-coated tibial components and were followed for two years with radiostereometric analysis exams to quantify the migration of the component. RESULTS: While there was significant variation in individual migration patterns, the overall migration of the tibial component in the study group demonstrated a pattern of initial migration followed by stabilisation after one year, with mean maximum total point motion (MTPM) of 0.02 mm (standard deviation (sd) 0.20) between one and two years post-operatively. The direction of greatest motion was subsidence, which stabilised at three months post-operatively (mean translation of 0.21 mm, sd 0.40). CONCLUSION: The tibial component migration pattern of stabilisation in the second post-operative year is indicative of successful long-term fixation for this PA-coated tibial component. Cite this article: Bone Joint J 2017;99-B:1596-1602.

Coping style and substance use intention and behavior patterns in a cohort of BC adolescents.

Adolescence is a developmental period during which young teenagers are particularly susceptible to shifting from well-defined behavioral intentions to abstain from substance use to intentions that include experimentation with substance use and in many cases engagement substance use. Coping mechanisms are often an important determinant of adolescent well-being, and the style of coping adopted by the individual can influence positive or negative health behavior. The goal of this study was to examine how the levels of positive coping style (i.e., engagement) and negative coping style (i.e., disengagement) associated with increased risk for tobacco and marijuana use, and intentions to use among those who have never tried. Higher levels of engagement coping were associated with lower odds of tobacco and marijuana use (AOR=0.96 (95% CI: 0.94-0.98), p<0.001 and AOR=0.95 (95% CI: 0.93-0.97) p<0.001, respectively). Higher levels of disengagement coping were associated with greater odds of tobacco and marijuana use (AOR=1.03 (95% CI: 1.01-1.05), p<0.001 and AOR=1.05 (95% CI: 1.03-1.07), p<0.001, respectively). Engagement coping was also protective against the intention to use tobacco (AOR=0.97 (95% CI: 0.96-0.99), p<0.001) or marijuana (AOR=0.98 (95% CI: 0.96-0.99), p<0.01). These findings suggest that psychoeducational programs supporting the development of engagement oriented coping strategies may contribute not only to reductions in adolescents' use of tobacco and marijuana, but also to reductions in adolescents' intentions to use in the future.

Quantifying Canadians' use of the Internet as a source of information on behavioural risk factor modifications related to cancer prevention.

INTRODUCTION: The purpose of this study was to quantify the frequency and timing of Canadians' Internet searches for information on modifying cancer prevention-related behavioural risk factors. METHODS: We used the Google AdWords Keyword tool to estimate the number of Internet searches in Canada from July 2010 to May 2011 for content associated with the keywords "physical activity / exercise," "healthy eating / weight loss" and "quit smoking." RESULTS: For "physical activity / exercise," 663 related keywords resulted in 117 951 699 searches. For "healthy eating / weight loss," 687 related search terms yielded 98 277 954 searches. "Quit smoking" was associated with 759 related keywords with 31 688 973 searches. All search patterns noticeably peaked in January 2011. CONCLUSION: Many Canadians are actively searching for information on the Internet to support health behaviour change associated with cancer prevention, especially during the month of January. To take advantage of this opportunity, key stakeholders in cancer prevention need to identify knowledge translation priorities and work with health agencies to develop evidence-based strategies to support Internet-facilitated behaviour change.

TITLE: Quantifier l'utilisation que les Canadiens font d'Internet comme source d'information sur la modification de certains comportements, identifiés comme facteurs de risque modifiables du cancer. INTRODUCTION: La présente étude visait à quantifier la fréquence à laquelle les Canadiens consultent Internet pour trouver des renseignements sur la modification de comportements qui sont des facteurs de risque modifiables du cancer, et à déterminer le moment choisi pour effectuer leurs recherches. MÉTHODOLOGIE: Nous avons utilisé l'outil générateur de mots clés Keywords du programme AdWords de Google pour estimer le nombre de recherches effectuées sur Internet au Canada entre juillet 2010 et mai 2011 pour trouver des renseignements associés aux mots clés anglais « physical activity/exercise ¼, « healthy eating/weight loss ¼ et « quit smoking ¼. RÉSULTATS: Dans le cas de « physical activity/exercise ¼, 663 mots clés connexes ont donné lieu à 117 951 699 recherches. Pour ce qui est de « healthy eating/weight loss ¼, 687 termes apparentés ont conduit à 98 277 954 recherches. « Quit smoking ¼ a été associé à 759 mots clés, qui ont mené à 31 688 973 recherches. Toutes ces recherches ont atteint un pic en janvier 2011. CONCLUSION: De nombreux Canadiens font, surtout en janvier, des recherches sur Internet à propos de certains changements de comportements de santé. Ces changements étant susceptibles de favoriser la prévention du cancer, les principaux intervenants dans ce domaine devraient en tirer profit, définir des priorités en matière de transfert des connaissances et travailler avec les organismes de santé à l'élaboration de stratégies fondées sur des données probantes, stratégies favorisant l'utilisation d'Internet pour encourager ces changements de comportement.

An examination of the smoking identities and taxonomies of smoking behaviour of youth.

OBJECTIVE: To address observations that the smoking identities of youth are valid descriptors of their smoking behaviour, we examined the relationships between self-reported smoking identities, perceived levels of addiction, and established taxonomies of smoking behaviour of youth. METHOD: Cross-sectional data were collected on demographics, perceived extent of addiction to tobacco, smoking history, and self-reported smoking identity from questionnaires administered to 8225 students in British Columbia, Canada. A total of 7246 participants were categorised according to four smoking taxonomies established in the literature. Differences in perceived physical and mental addiction between smoking identity groups were calculated. The strength of the associations between the taxonomies of smoking and the smoking identity groups was also assessed. RESULTS: There were significant differences in perceived levels of physical (Kruskal-Wallis chi(2) = 3985.02, p<0.001) and mental (Kruskal-Wallis chi(2) = 4046.09, p<0.001) addiction to tobacco by the participants' self-reported smoking identity. Youth smoking identities were modestly associated with the established smoking taxonomies (Pearson C contingency coefficient = 0.64-0.72). CONCLUSION: Self-reported smoking identities appear to provide valid characterisation of the smoking behaviour of youths that complement and elaborate existing taxonomies of smoking behaviour. Questions about self-reported smoking identity should be used in conjunction with smoking behaviour taxonomies when investigating youth smoking behaviours.

A randomized, double-blind study of triple nucleoside therapy of abacavir, lamivudine, and zidovudine versus lamivudine and zidovudine in previously treated human immunodeficiency virus type 1-infected children. The CNAA3006 Study Team.

OBJECTIVES: Abacavir (ABC) is a potent inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase. We compared the efficacy, safety, and tolerability of combination therapy with ABC, lamivudine (3TC), and zidovudine (ZDV) versus 3TC and ZDV in antiretroviral experienced HIV-1-infected children over 48 weeks. METHODS: Two hundred five HIV-1-infected children who had received previous antiretroviral therapy and had CD4(+) cell counts >/=100 cells/mm(3) were stratified by age and by previous treatment. Participants were randomly assigned to receive ABC (8 mg/kg twice daily [BID]) plus 3TC (4 mg/kg BID) and ZDV (180 mg/m(2) BID; ABC/3TC/ZDV group) or ABC placebo plus 3TC (4 mg/kg BID) and ZDV (180 mg/m(2); 3TC/ZDV group). Participants who met a protocol-defined switch criteria (plasma HIV-1 RNA >0.5 log(10) copies/mL above baseline at week 8 or >10 000 copies/mL after week 16) had the option to switch to open-label ABC plus any antiretroviral combination or continue randomized therapy or withdraw from the study. RESULTS: The Kaplan-Meier estimates (95% confidence interval) of the proportion of participants who maintained HIV-1 RNA levels 10 000 copies/mL, a significantly higher proportion of participants in the ABC/3TC/ZDV group had HIV-1 RNA