Understanding the bigger picture: syndemic interactions of the immigrant and refugee context with the lived experience of diabetes and obesity.

BACKGROUND: Providing contextually appropriate care and interventions for people with diabetes and/or obesity in vulnerable situations within ethnocultural newcomer communities presents significant challenges. Because of the added complexities of the refugee and immigrant context, a deep understanding of their realities is needed. Syndemic theory sheds light on the synergistic nature of stressors, chronic diseases and environmental impact on immigrant and refugee populations living in vulnerable conditions. We used a syndemic perspective to examine how the migrant ethnocultural context impacts the experience of living with obesity and/or diabetes, to identify challenges in their experience with healthcare. METHODS: This qualitative participatory research collaborated with community health workers from the Multicultural Health Brokers Cooperative of Edmonton, Alberta. Study participants were people living with diabetes and/or obesity from diverse ethnocultural communities in Edmonton and the brokers who work with these communities. We conducted 3 focus groups (two groups of 8 and one of 13 participants) and 22 individual interviews (13 community members and 9 brokers). The majority of participants had type 2 diabetes and 4 had obesity. We conducted a thematic analysis to explore the interactions of people's living conditions with experiences of: 1) diabetes and obesity; and 2) healthcare and resources for well-being. RESULTS: The synergistic effects of pre- and post-immigration stressors, including lack of social network cultural distance, and poverty present an added burden to migrants' lived experience of diabetes/obesity. People need to first navigate the challenges of immigration and settling into a new environment in order to have capacity to manage their chronic diseases. Diabetes and obesity care is enhanced by the supportive role of the brokers, and healthcare providers who have an awareness of and consideration for the contextual influences on patients' health. CONCLUSIONS: The syndemic effects of the socio-cultural context of migrants creates an additional burden for managing the complexities of diabetes and obesity that can result in inadequate healthcare and worsened health outcomes. Consequently, care for people with diabetes and/or obesity from vulnerable immigrant and refugee situations should include a holistic approach where there is an awareness of and consideration for their context.

The impact of a temporary recurrent street closure on physical activity in New York City.

At least 70 US cities have now introduced ciclovías-large-scale street closures to promote physical activity-joining numerous other cities worldwide that have implemented ciclovías in efforts to improve population health. We assessed the impact of Summer Streets, a New York City program in which 6.9 contiguous miles of urban streets were closed to traffic and opened for walking, cycling, and group activities, such as dancing and yoga, on population physical activity levels. Screen line counts were used to estimate attendance, and a street intercept survey was conducted to assess demographic characteristics of participants, baseline adherence to physical activity recommendations, and type and duration of physical activity at Summer Streets. In addition, a traffic study was used to determine if there were vehicular traffic delays as a result of the program. About 50,000 people participated in Summer Streets; among participating New Yorkers, bicyclists averaged 6.7 miles, runners 4.3 miles, and walkers 3.6 miles, equivalent to 72-86 min of moderate physical activity. Among New Yorkers attending Summer Streets, 24 % reported that they did not routinely engage in moderate- or vigorous-intensity physical activity. These non-routine exercisers engaged in the equivalent of 26-68 min of moderate-intensity physical activity at Summer Streets. Summer Streets served as an enticement for New Yorkers, including those who did not ordinarily meet physical activity recommendations, to engage in physical activity. There were no significant vehicular traffic delays during the program.

Self-reported sitting time in New York City adults, the Physical Activity and Transit Survey, 2010-2011.

INTRODUCTION: Recent studies have demonstrated the negative health consequences associated with extended sitting time, including metabolic disturbances and decreased life expectancy. The objectives of this study were to characterize sitting time in an urban adult population and assess the validity of a 2-question method of self-reported sitting time. METHODS: The New York City Health Department conducted the 2010-2011 Physical Activity and Transit Survey (N = 3,597); a subset of participants wore accelerometers for 1 week (n = 667). Self-reported sitting time was assessed from 2 questions on time spent sitting (daytime and evening hours). Sedentary time was defined as accelerometer minutes with less than 100 counts on valid days. Descriptive statistics were used to estimate the prevalence of sitting time by demographic characteristics. Validity of sitting time with accelerometer-measured sedentary time was assessed using Spearman's correlation and Bland-Altman techniques. All data were weighted to be representative of the New York City adult population based on the 2006-2008 American Community Survey. RESULTS: Mean daily self-reported sitting time was 423 minutes; mean accelerometer-measured sedentary time was 490 minutes per day (r = 0.32, P < .001). The mean difference was 49 minutes per day (limits of agreement: -441 to 343). Sitting time was higher in respondents at lower poverty and higher education levels and lower in Hispanics and people who were foreign-born. CONCLUSION: Participants of higher socioeconomic status, who are not typically the focus of health disparities-related research, had the highest sitting times; Hispanics had the lowest levels. Sitting time may be accurately assessed by self-report with the 2-question method for population surveillance but may be limited in accurately characterizing individual-level behavior.

Developing built environment programs in local health departments: lessons learned from a nationwide mentoring program.

Local health departments (LHDs) have a key role to play in developing built environment policies and programs to encourage physical activity and combat obesity and related chronic diseases. However, information to guide LHDs' effective engagement in this arena is lacking. During 2011-2012, the New York City Department of Health and Mental Hygiene (DOHMH) facilitated a built environment peer mentoring program for 14 LHDs nationwide. Program objectives included supporting LHDs in their efforts to achieve built environment goals, offering examples from DOHMH's built environment work to guide LHDs, and building a healthy built environment learning network. We share lessons learned that can guide LHDs in developing successful healthy built environment agendas.

Associations between building design, point-of-decision stair prompts, and stair use in urban worksites.

OBJECTIVE: Incidental forms of physical activity such as stair use offer frequent opportunities for energy expenditure and may contribute to the prevention and control of chronic diseases. This study analyzes the associations between building characteristics, stair prompts, and stair use in large urban worksites. METHODS: Bootstrapped generalized mixed models were used to analyze self-reported stair use, using data from 1348 surveys of city employees and fourteen building assessments conducted in New York City in 2012. RESULTS: 57% of respondents reported climbing ≥1 flights of stairs daily at the workplace. Model results show that stair prompts were associated with a 3.21 increased likelihood of stair use. Naturally lit stairwells and stairwell visibility were also positively associated. Higher floor residency and BMI were negatively related, as were gender, stairwell distance from lobby entrances, the total number of floors in each building, and building averages for BMI and gender. Residual heterogeneity measured by adjusted median odds ratios indicates that buildings can have a moderate effect on the likelihood of stair use beyond those of individual characteristics. CONCLUSIONS: Specific building features and stair prompts may potentially be leveraged to positively influence rates of incidental physical activity and contribute to improvements in population health.

Building safety into active living initiatives.

OBJECTIVE: Efforts to promote environmental designs that facilitate opportunities for physical activity should consider the fact that injuries are the leading cause of death for Americans ages 1 to 44, with transportation-related injuries the most common cause. Drawing on the latest research and best practices in the field of injury prevention, the purpose of this article is to provide those working to promote physical activity with evidence-based recommendations on building in safety while designing active environments. METHOD: A systematic review of the peer-reviewed and grey literature published from 1995 to 2012 was conducted to identify injury prevention strategies applicable to objectives in the Active Design Guidelines (ADG), which present design strategies for active living. Injury prevention strategies were rated according to the strength of the research evidence. RESULTS: We identified 18 urban design strategies and 9 building design strategies that promote safety. Evidence was strong or emerging for 14/18 urban design strategies and 7/9 building design strategies. CONCLUSION: ADG strategies are often wholly compatible with well-accepted injury prevention principles. By partnering with architects and planners, injury prevention and public health professionals can help ensure that new and renovated spaces maximize both active living and safety.

Neighborhood safety and green space as predictors of obesity among preschool children from low-income families in New York City.

BACKGROUND: Neighborhood safety, green space, walkability, and sociodemographics may influence physical activity and childhood obesity. METHODS: Data on measured height and weight, demographic characteristics, and home ZIP code were collected from year 2004 enrollees in a means-tested preschool program in New York City. Each ZIP code was surrounded by a 400-m buffer and characterized using data from the US census, local government departments, New York Times website, and Transportation Alternatives. Linear and Poisson models were constructed using cluster robust standard errors and adjusting for child's sex, race, ethnicity, age, and neighborhood characteristics. RESULTS: Analyses included 11,562 children ages 3-5 years living in 160 residential ZIP codes. A higher homicide rate (at the 75th vs 25th percentile) was associated with a 22% higher prevalence of obesity (95% CI for the prevalence ratio (PR): 1.05 to 1.41). A higher density of street trees (at the 75th vs 25th percentile) was associated with 12% lower prevalence of obesity (95% CI for the PR: 0.79 to 0.99). Other neighborhood characteristics did not have significant associations with childhood obesity. CONCLUSIONS: Among preschool children from low-income families, neighborhood homicide rate was associated with more obesity and street tree density was associated with less obesity.

Impact of an Urban Project ECHO: Safety-Net Clinician Self-Efficacy Across Conditions.

INTRODUCTION: To mitigate the lack of specialty healthcare, Project ECHO (Extension for Community Health Outcomes) trains community-based primary care clinicians to better prevent the progression of, manage, and treat common health conditions. ECHO-Chicago launched in 2010 as the first urban-centered ECHO program, focusing on safety-net clinicians, and has trained over 5,175 community clinicians across 34 topic areas. This paper examines self-efficacy among ECHO-Chicago participants across 11 clinical series, including a novel use of qualitative themes from self-efficacy questions. METHODS: Five years of baseline and postseries survey data were collected from 2014 to 2019, resulting in 951 participants. Paired t-tests assessed change from baseline survey to postsurvey, and Cohen's d determined effect size. Change was assessed by individual series, adult or pediatric focus, participants' prescription privilege status, and across series by qualitative question theme. Metrics included total change, any improvement, a 10% target, and a clinical competency threshold. Analysis occurred from July 2020 to January 2022. RESULTS: All clinical series achieved statistically significant improvement in self-efficacy, and most had a large effect size. A total of 88% had any improvement, 65% met the 10% target of 0.7 points, and 52% met the competency threshold of 5.0 in the postsurvey. Prescribers had a significantly greater increase in their self-efficacy scores than nonprescribers. With a comparison across series, each theme achieved statistical significance, with most reaching large effect sizes. CONCLUSIONS: ECHO-Chicago successfully increased participants' self-efficacy. This inquiry adds an urban focus, years of data, multiple series, and a novel qualitative theme component to enable comparisons across rather than solely within the ECHO series.

Health care providers' perspectives on challenges and opportunities of intercultural health care in diabetes and obesity management: a qualitative study.

BACKGROUND: Migrants often face worse health outcomes in countries of transit and destination because of challenges such as financial constraints, employment problems, lack of a network of social support, language and cultural differences, and difficulties accessing health services. As understanding how the migrant context affects patient-provider engagement is critical to the provision of contextually appropriate care, this study aimed at understanding primary health care provider perspectives on challenges and opportunities of the intercultural care process for migrant patients with diabetes and obesity. METHODS: This qualitative study within a multimethod, participatory research project involved primary care providers in clinics and primary care networks in Edmonton, Alberta, between September 2019 and February 2020. We explored health care providers' approaches to diabetes and obesity management, and experiences of and challenges with intercultural care. We conducted a thematic analysis using an interpretive qualitative approach. RESULTS: We conducted 9 interviews and 4 focus groups and identified 3 themes: a shift from traditional weight loss-centred approaches; relationships and navigating cultural distance; and importance of and limitations in identifying and addressing root causes and barriers. Health care providers encounter considerable nonmedical challenges when supporting immigrant patients, such as navigating cultural distance and working with patients' financial constraints. INTERPRETATION: The nonmedical challenges we identified can hinder the process of chronic disease management. Thus, in addition to educational programs and trainings to enhance the cultural competency of health care providers, incorporating avenues for cultural brokering in health care can provide invaluable support in patient-provider engagements to mitigate these challenges.

Role of cultural brokering in advancing holistic primary care for diabetes and obesity: a participatory qualitative study.

OBJECTIVES: Diabetes and obesity care for ethnocultural migrant communities is hampered by a lack of understanding of premigration and postmigration stressors and their impact on social and clinical determinants of health within unique cultural contexts. We sought to understand the role of cultural brokering in primary healthcare to enhance chronic disease care for ethnocultural migrant communities. DESIGN AND SETTING: Participatory qualitative descriptive-interpretive study with the Multicultural Health Brokers Cooperative in a Canadian urban centre. Cultural brokers are linguistic and culturally diverse community health workers who bridge cultural distance, support relationships and understanding between providers and patients to improve care outcomes. From 2019 to 2021, we met 16 times to collaborate on research design, analysis and writing. PARTICIPANTS: Purposive sampling of 10 cultural brokers representing eight different major local ethnocultural communities. Data include 10 in-depth interviews and two observation sessions analysed deductively and inductively to collaboratively construct themes. RESULTS: Findings highlight six thematic domains illustrating how cultural brokering enhances holistic primary healthcare. Through family-based relational supports and a trauma-informed care, brokering supports provider-patient interactions. This is achieved through brokers' (1) embeddedness in community relationships with deep knowledge of culture and life realities of ethnocultural immigrant populations; (2) holistic, contextual knowledge; (3) navigation and support of access to care; (4) cultural interpretation to support health assessment and communication; (5) addressing psychosocial needs and social determinants of health and (6) dedication to follow-up and at-home management practices. CONCLUSIONS: Cultural brokers can be key partners in the primary care team to support people living with diabetes and/or obesity from ethnocultural immigrant and refugee communities. They enhance and support provider-patient relationships and communication and respond to the complex psychosocial and economic barriers to improve health. Consideration of how to better enable and expand cultural brokering to support chronic disease management in primary care is warranted.

An Umbrella Review of the Best and Most Up-to-Date Evidence on the Built Environment and Physical Activity in Older Adults ≥60 Years.

Objectives: To present the best and most up-to-date evidence on associations between built environment (BE) attributes and overall and specific domains of physical activity (PA) (i.e., leisure, transport, walking, and cycling) in older adults (≥60 years). Methods: An umbrella review was undertaken to compile evidence from systematic reviews using the Joanna Briggs Institute methodology. A comprehensive search (updated 16 August 2022), inclusion/exclusion of articles via title/abstract and full-text reviews, data extraction, and critical appraisal were completed. Only reviews with a good critical appraisal score were included. Results: Across three included systematic reviews, each BE attribute category was positively associated with ≥1 PA outcome. A larger number of significant associations with BE attributes were reported for transport walking (13/26), total walking (10/25), and total PA (9/26), compared to leisure walking (4/34) and transport cycling (3/12). Fewer associations have been examined for leisure cycling (1/2). Conclusion: Although the causality of findings cannot be concluded due to most primary studies being cross-sectional, these best and most up-to-date findings can guide necessary future longitudinal and experimental studies for the (re)design of age-friendly communities.

Individual- and school-level sociodemographic predictors of obesity among New York City public school children.

To identify student- and school-level sociodemographic characteristics associated with overweight and obesity, the authors conducted cross-sectional analyses of data from 624,204 public school children (kindergarten through 12th grade) who took part in the 2007-2008 New York City Fitnessgram Program. The overall prevalence of obesity was 20.3%, and the prevalence of overweight was 17.6%. In multivariate models, the odds of being obese as compared with normal weight were higher for boys versus girls (odds ratio (OR) = 1.39, 95% confidence interval (CI): 1.36, 1.42), for black (OR = 1.11, 95% CI: 1.07, 1.15) and Hispanic (OR = 1.48, 95% CI: 1.43, 1.53) children as compared with white children, for children receiving reduced-price (OR = 1.17, 95% CI: 1.13, 1.21) or free (OR = 1.12, 95% CI: 1.09, 1.15) school lunches as compared with those paying full price, and for US-born students (OR = 1.54, 95% CI: 1.50, 1.58) as compared with foreign-born students. After adjustment for individual-level factors, obesity was associated with the percentage of students who were US-born (across interquartile range (75th percentile vs. 25th), OR = 1.10, 95% CI: 1.07, 1.14) and the percentage of students who received free or reduced-price lunches (across interquartile range, OR = 1.13, 95% CI: 1.10, 1.18). The authors conclude that individual sociodemographic characteristics and school-level sociodemographic composition are associated with obesity among New York City public school students.

Trends in obesity across Canada from 2005 to 2018: a consecutive cross-sectional population-based study.

BACKGROUND: Obesity is increasingly prevalent worldwide and is becoming an epidemic in many countries, including Canada. We sought to describe and analyze temporal obesity trends in the Canadian adult population from 2005 through 2018 at the national and provincial or territorial levels. METHODS: We conducted a consecutive, cross-sectional study using data from 7 sequential Canadian Community Health Survey (CCHS) cycles (2005 to 2017/18). We included data from Canadian adults (age ≥ 18 yr) who participated in at least 1 of the 7 consecutive CCHS cycles and who had body mass index values (calculated by Statistics Canada based on respondents' self-reported weight and height). Obesity prevalence (adjusted body mass index ≥ 30) was a primary outcome variable. We analyzed temporal trends in obesity prevalence using Pearson χ2 tests with Bonferroni adjustment, and the Cochran-Armitage test of trend. RESULTS: We included data from 746 408 (403 582 female and 342 826 male) CCHS participants. Across Canada, the prevalence of obesity increased significantly between 2005 and 2017/18, from 22.2% to 27.2% (p < 0.001). We observed increases across both sexes, all age groups and all Canadian provinces and territories (p < 0.001). In 2017/18, the prevalence of obesity was higher among males than females (28.9% v. 25.4%; p < 0.001); the prevalence among adults aged 40-69 years exceeded 30%. In 2017/18, Newfoundland and Labrador had the highest prevalence (39.4%), and British Columbia had the lowest (22.8%) prevalence of obesity. Over the 14-year study period, Quebec and Alberta exhibited the largest relative increases in obesity. INTERPRETATION: In 2017/18, more than 1 in 4 adult Canadians lived with obesity, and from 2005 to 2017/18, the prevalence of obesity among adults in Canada increased substantially across sexes, age groups and all Canadian provinces and territories to 27.2%. Our findings call for urgent actions to identify, implement and evaluate solutions for obesity prevention and management in all Canadian provinces and territories.

Protocol for an evaluation of the Designing Communities to Support Healthy Living in Aging Residents Study.

BACKGROUND: In collaboration with building developers, the Housing for Health team is contributing to the design of community-based congregate living facilities to support healthy living in older adults. There may also be opportunities to improve the surrounding neighbourhoods by collaborating with the municipalities where the developments are located. We will evaluate whether one or more of these comprehensive interventions lead to changes in the perceived, microscale, and macroscale neighbourhood-built environment (BE) and amenities, and impacts on the physical activity (PA), healthy eating, and social connections of residents. In parallel, we will gather qualitative data to provide a more in-depth understanding of how the BE may facilitate or hinder resident's healthy living outcomes. METHODS: This project employs a quasi-experimental pre-post design with at least one or more intervention and control sites. The quantitative BE evaluation will include pre- and post-intervention assessments of neighbourhood macroscale (e.g., layout of communities) and microscale (e.g., street details and characteristics) changes using Geographical Information Systems (GIS) and Microscale Audit Pedestrian Streetscapes (MAPS) audits, respectively. The quantitative resident evaluation will include self-report (i.e., surveys) and objective assessments (i.e., accelerometers, Global Positioning System [GPS]) of residents at baseline (3-6-months pre-move-in) and follow-up (3-6-months and 9-12-months post-move-in if possible). The qualitative resident-environment component will involve in-depth semi-structured interviews post-intervention with building residents, family members, and stakeholders involved in the design/development and/or operation of the intervention site(s). Participant observations will be completed in the building and neighbourhood environments of the intervention site(s). DISCUSSION: Findings will provide evidence on whether and how comprehensive changes to the BE and amenities of at least one congregate living facility and the surrounding neighbourhood can impact PA, healthy eating, and social connections of older adults. Successful intervention elements will be scaled up in future work. We will disseminate findings to a broad audience including the scientific community via peer-reviewed publications, conference presentations, and discussion panels; and the private, public, and not-for-profit sectors via reports, public presentations, and/or communications via our partners and their networks. TRIAL REGISTRATION: Protocol ID: 1819-HQ-000051. ClinicalTrials.gov ID: NCT05031273. Registered 29 June 2021 with ClinicalTrials.gov.

Intrinsic motivation as a mediator of relationships between symptoms and functioning among individuals with schizophrenia spectrum disorders in a diverse urban community.

This study investigated intrinsic motivation as a mediator of the relationship between clinical symptoms and functioning. The mediation model was tested with a sample of 166 adults with schizophrenia spectrum disorders attending psychosocial rehabilitation programs in a diverse urban community. Ethnic minority status was examined as a moderator of the mediation model. Motivation was measured using items reflecting intrapsychic drive. Symptoms were assessed with the expanded Brief Psychiatric Rating Scale and functioning with the Role Functioning Scale. Motivation was a significant mediator of the relationship between functioning and all symptom scores; fully mediating the relationship between functioning and negative, disorganized, and global symptoms, and partially mediating the relationship between positive symptoms and functioning. Motivation scores between ethnic minority and nonminority individuals differed significantly (p < 0.05), but no moderation effect was indicated. The strong mediation effect schizophrenia of motivation on the symptoms-functioning relationship supports future work to translate findings into effective recovery-oriented services.

Accelerometer and Survey Data on Patterns of Physical Inactivity in New York City and the United States.

OBJECTIVE: Inactive lifestyles contribute to health problems and premature death and are influenced by the physical environment. The primary objective of this study was to quantify patterns of physical inactivity in New York City and the United States by combining data from surveys and accelerometers. METHODS: We used Poisson regression models and self-reported survey data on physical activity and other demographic characteristics to predict accelerometer-measured inactivity in New York City and the United States among adults aged ≥18. National data came from the 2003-2004 and 2005-2006 National Health and Nutrition Examination Surveys. New York City data came from the 2010-2011 New York City Physical Activity and Transit survey. RESULTS: Self-reported survey data indicated no significant differences in inactivity between New York City and the United States, but accelerometer data showed that 53.1% of persons nationally, compared with 23.4% in New York City, were inactive ( P < .001). New Yorkers reported a median of 139 weekly minutes of transportation activity, compared with 0 minutes nationally. Nationally, 50.0% of self-reported activity minutes came from recreation activity, compared with 17.5% in New York City. Regression models indicated differences in the association between self-reported minutes of transportation and recreation and accelerometer-measured inactivity in the 2 settings. CONCLUSIONS: The prevalence of physical inactivity was higher nationally than in New York City. The largest difference was in walking behavior indicated by self-reported transportation activity. The study demonstrated the feasibility of combining accelerometer and survey measurement and that walkable environments promote an active lifestyle.

Lessons learned from the development and implementation of a citywide stair prompt initiative.

Stair climbing is a readily available form of vigorous-intensity physical activity. Evidence indicates that placing stair prompt signs at points-of-decision (e.g. near elevators and stairways) is an inexpensive, effective strategy for increasing physical activity through stair use. This article aims to share the experience of the New York City Department of Health and Mental Hygiene (NYC DOHMH) in the outreach and implementation of a population-scale stair prompt initiative, including lessons learned from process evaluations, with other public health authorities conducting a similar program. Between May 2008 and August 2012, NYC DOHMH implemented a stair prompt initiative as one strategy in a comprehensive program to increase physical activity and healthy eating through physical improvements to NYC's buildings, streets and neighborhoods, particularly targeting facilities in underserved and low-income neighborhoods. Program evaluation was conducted using program planning documents to examine the process, and data from NYC information line call center, outreach tracking database, and site and phone audits to examine process outcomes. The initiative successfully distributed more than 30,000 stair prompts to building owners/managers of over 1000 buildings. Keys to success included multi-sector partnerships between NYC's Health Department and non-health government agencies and organizations (such as architecture and real estate organizations), a designated outreach coordinator, and outreach strategies targeting building owners/managers owning/managing multiple buildings and buildings serving underserved and at risk populations. A NYC citywide initiative successfully distributed stair prompts to the wider community to promote population-level health impacts; lessons learned may assist other jurisdictions considering similar initiatives to increase physical activity.

Design strategies and rigorous conditions for single-polarization single-mode waveguides.

We establish rigorous necessary analytical conditions for the existence of single-polarization single-mode (SPSM) bandwidths in index-guided microstructured waveguides (such as photonic-crystal fibers). These conditions allow us to categorize designs for SPSM waveguides into four strategies, at least one of which seems previously unexplored. Conversely, we obtain rigorous sufficient conditions for the existence of two cutoff-free index-guided modes in a wide variety of microstructured dielectric waveguides with arbitrary periodic claddings, based on the existence of a degenerate fundamental mode of the cladding (a degenerate light line). We show how such a degenerate light line, in turn, follows from the symmetry of the cladding.

Rigorous sufficient conditions for index-guided modes in microstructured dielectric waveguides.

We derive a sufficient condition for the existence of index-guided modes in a very general class of dielectric waveguides, including photonic-crystal fibers (arbitrary periodic claddings, such as "holey fibers"), anisotropic materials, and waveguides with periodicity along the propagation direction. This condition provides a rigorous guarantee of cutoff-free index-guided modes in any such structure where the core is formed by increasing the index of refraction (e.g. removing a hole). It also provides a weaker guarantee of guidance in cases where the refractive index is increased "on average" (precisely defined). The proof is based on a simple variational method, inspired by analogous proofs of localization for two-dimensional attractive potentials in quantum mechanics.