Niskar AS, Needham LL, Rubin C, Turner WE, Martin CA, Patterson DG Jr, et al. 2009. Serum dioxins, polychlorinated biphenyls, and endometriosis: a case-control study in Atlanta. Chemosphere 74:944–949.
As noted earlier, the lack of information on the prevalence of co-morbid conditions among decedents limits our ability to draw conclusions about co-morbid conditions as a risk factor for death during heat waves. Similarly, it would be advantageous to have individual-level socioeconomic status data, in addition to the neighborhood measure used in the present study. We used outdoor ambient temperature as a proxy for personal exposure to heat, though the amount of time that individuals spend indoors may have contributed to error in this exposure metric. Furthermore, we did not have access to data about the residential interior that could have predicted mortality, such as air conditioning use and apartment floor, which have both been cited as important predictors of heat-related mortality (; ). A recent telephone survey indicated that approximately 11% of New Yorkers do not have a functioning air conditioner, and an additional 14% do not use their air conditioner regularly (). Finally, the case-only method is useful for identifying groups with a greater relative risk of death associated with heat waves and does not necessarily identify groups with the greatest absolute excess risk. For example, seniors have much higher daily mortality rates and may have a higher absolute excess risk than younger adults despite not having a higher relative risk.
Where can it go wrong?
There are everywhere in content creation. Here are a few things you shouldn’t do with your case study.
Let it get stale—Don’t let your case study get outdated. If you have new information you can add or dates or statistics to refresh, do it. If readers believe your material is old, they become dubious that the story is still relevant.
Results—Choose a case study that has compelling results. Show as much in the way of metrics, KPIs, and ROI as possible. But remember that some results will be concrete, and some will be more focused on brand awareness. A quote from the client about how results affected their business will help. This can be more powerful than any metrics.
Although findings from several studies suggest that the elderly are more susceptible to heat-related mortality (; ; ), we did not find evidence of a greater relative increase in mortality during heat waves among the elderly in this study, consistent with a multi-city study (). Complex interactions among age, race, and other susceptibility factors may have led to confounding in our data and may partially account for our failure to find an association between age and heat-related mortality. Another hypothesis is that there may be other demographic shifts that have made the elderly in NYC more resilient in the past decade. Future analyses will examine this by looking at changes in vulnerability over time. Likewise, although heat has often been associated with cardiovascular disease (CVD) mortality (), our results do not show evidence of increased risk of mortality for those dying of CVD. In fact, the relative odds of a death from CVD appear to be lower during heat waves in our study. Our findings do not demonstrate that persons dying of CVD do not have an increased risk of dying during heat waves, but rather that the risk of CVD-related death increases less than the risk of death from other causes.
In our study, the possibility existed for controls to have undiagnosed disease, because the absence of endometriosis was not confirmed surgically in controls in the parent WREN study. However, the prevalence of undiagnosed endometriosis that meets the case definition of endometriotic disease is likely to be small, possibly ).
We also found the suggestion of increased endometriosis risk associated with serum concentrations of mirex, assuming that the measurement of mirex after diagnosis in cases is representative of exposure during the etiologically relevant time window. Mirex was used in the 1960s and 1970s as part of an insect control program against fire ants, with aerial application on millions of acres of southeastern U.S. states, and the chemical also was used as a fire-retardant additive. With a half-life of up to 10 years, mirex is considered one of the most stable and persistent pesticides (; ). In our study of U.S. Pacific Northwest health plan enrollees, only 38.2% of mirex concentration measurements were above the LOD, indicating that this potential risk factor would be unlikely to be a major contributor to endometriosis incidence in our population. However, the investigation of mirex in relation to endometriosis remains relevant because some populations may be exposed to greater concentrations of mirex, such as those who consume fish from mirex-contaminated lakes and waterways of the Great Lakes and those residing in arctic regions, particularly indigenous populations (; ; ). One study reported the detection of mirex concentrations in the sera of Inuit populations of Greenland and Canada, ranging from 86% to 97% (). Mirex has also been detected in the sera of 85.9% of pregnant women in an agricultural community in California (), suggesting that other populations also may have increased mirex exposure. The association we found between serum concentrations of mirex and endometriosis risk contrasts with the results of three small prior studies; one study of 29 cases and 51 controls reported null results () and two studies reported no statistically significant difference in lipid-adjusted serum concentrations between 58 cases and 81 controls () and 86 cases and 70 controls (). All three of these case–control studies were conducted among laparoscopic patients. Additionally, given the small sample sizes, these studies may have been underpowered to detect an association.
For a translatathon the choice of subject needs to be something that is both underrepresented and that participants can relate to. Given that the people in this case were almost all women and enrolled on a programme with a technical and medical focus, women’s health was a good choice.
We found that cases and controls were similar demographically, except that cases were more likely to be of Hispanic ethnicity (). Additionally, cases were more likely than controls to be current alcohol consumers and nulliparous, less likely to have a history of breastfeeding for > 1 year, and had greater serum lipid concentrations. The distribution of characteristics in this subset of WREN participants was similar to that found among WREN cases and controls in the parent study (data not shown). The demographic and lifestyle characteristics among controls of the WREN study closely mirror those of the general population in the surrounding Puget Sound region ()
Given the number of statistical tests carried out in this study, it is possible that some of our findings were attributable to chance. It is also possible that our results were affected by misclassification of exposure. Similar to previous studies of serum and adipose tissue concentrations of OCPs and endometriosis, serum samples in our study were obtained after disease onset, a median of 1.2 years after the diagnosis date (range 6 months to 5.8 years), and serum OCP concentrations may not reflect OCP body burden at the time of disease development and progression. The timing of sample collection may have resulted in an underestimate of exposure in women who subsequently gave birth or breastfed, factors that may reduce OCP body burden (; ). Because parity and breastfeeding may be intermediates in the causal pathway between exposure and disease, or may be affected by endometriosis, we decided a priori not to adjust for these factors in the main analyses. In our exploratory analyses considering an alternative conceptual framework with parity and breastfeeding as confounders, ORs were generally lower than estimates from our main analyses that were not adjusted for these factors. However, in both sets of analyses, we observed a positive association between β-HCH and ovarian endometriosis.