Incidents cases

Stolt P. et al., Quantification of the influence of cigarette smoking on rheumatoid arthritis results from a population based case-control study, using incident cases, Am. Rheum. Dis., 62, 835, 2003. 

Initially, the literature is searched for relevant data on the substance (physical-chemical properties, thermodynamics, incidents, case studies, and so forth). If insufficient data are available, the usual case, a systematic investigation procedure comprising three main subjects must be initiated for the material in question. 

The U.S. Chemical Safety and Hazard Investigation Board (CSB) has conducted detailed investigations into a few chemical reactivity incidents. Case studies and full investigation reports are available from the CSB (Washington, DC) or its website (www.chemsafety.gov). Extracts from three CSB publications (1998,2002a, 2002c) are given here. 

Learning from incident case studies requires the ability to step back and examine the similarities and differences between a current situation and an incident that was experienced elsewhere. One should ask, Why can t the incident that happened at company x happen here Be alert for of action overload, that is, incident actions competing with existing actions from audits or other sources. A management team may be needed to prioritize multiple actions and their close-out. Learning from incident case studies also requires a willingness to change and adopt new and improved practices. Table 15-1 lists questions that can be applied to conduct a critical analysis of accident case studies. 

If incident case studies are periodically communicated to executives, they can help to reenforce the importance of doing things correctly. This typically translates into critical tasks that must he performed hy skilled workers and accoimtahility for those activities at an executive stewardship level. Such a commitment will carry over into incident investigation follow-up. 

Eisen et al (1994) USA Nested case-control of laryngeal cancer 108 fatal and incident cases 538 controls (study base Eisen et al., 1992 cohort) 1941-84 Cumulative exposure to straight and soluble types of metalworking fluid and metalworking fluid particulate exposure during grinding duration of exposure to metalworking fluid and other components. 

Arendt M, Rosenberg R, Foldager L, Perto G Minuk-Jorgensen P (2005). Cannabis-induced psychosis and subsequent schizophrenia-spectrum disorders follow-up study of 535 incident cases. British Journal of Psychiatry, 187, 510-15... 

Excess incident cases per million persons per rad per year, age-adjusted. 

In a cohort study (164) in 1785 women, 69 incident cases of diabetes mellitus were diagnosed, with an average incidence of 1.5 cases per 100 patient-years. In patients taking protease inhibitors, incidence rates were about twice as high (2.8 cases per 100 patient-years) as among users of NNRTIs or untreated patients (1.2%) and uninfected controls (1.4%). In a multivariate model use of protease inhibitors (HR = 2.9 1.5, 5.6), age, and BMI were independent risk factors for diabetes. 

The data cut-off point for this study was 31 August 2000. Only incident cases of diabetes mellitus that resulted in intervention with antidiabetic drugs were selected and only patients taking antipsychotic drug... 

Hulten, K., Winkvist, A., and Lenner, P. 2002. An incident case-referent study onplasma enterolac-tone and breast cancer risk. Eur. J. Nutr. 41(4), 168-176. 

For a trial period of 3 months, clothing submitted to the laboratory for inorganic FDR analysis was also examined for organic FDR. Organic residues detected during the trial period were not used as evidence in criminal proceedings. In all 13 different firearm-related incidents (cases FI through F13) a total of 186 exhibits were examined. One case FI accounted for 100 exhibits. The positive results are listed in Table 26.7. 

Rothwell PM, Coull AJ, Giles MF et al. (2004). Change in stroke incidence, mortality, case-fatality, severity and risk factors in Oxfordshire, UK from 1981 to 2004 (Oxford Vascular Study). Lancet 363 1925-1933 Rothwell PM, Coull AJ, Silver LE et al. (2005). Population-based study of event-rate, incidence, case fatality and mortality for all acute vascular events in all arterial territories (Oxford Vascular Study). 

Stegmayr B, Asplund K, Wester PO (1994). Trends in incidence, case fatality rate, and severity of stroke in Northern Sweden, 1985-1991. Stroke 25 1738-1745 Sudlow CLM, Warlow CP (1996). Comparing stroke incidence worldwide. What makes studies comparable Stroke 27 550-558 Sudlow CLM, Warlow CP (1997). Comparable studies of the incidence of stroke and its pathological types. Results from an international collahoration. Stroke 28 491-499... 

A prospective study of acute cerebrovascular disease in the community the Oxfordshire Community Stroke Project 1981-86. 2. Incidence, case fatality rates and overall outcome at one year of cerebral infarction, primary intracerebral and subarachnoid haemorrhage. Journal of Neurology, Neurosurgery and Psychiatry 53 16-22... 

Figure 7.1 The design of a cohort study and its relationship with case-control study designs. Individuals who died during follow-up in the shaded area are eligible for inclusion in a case-control study including incident cases between t and t2- The controls in the case-control study are individuals who did not have the disease of interest at the time of involvement. Arrows indicate end of follow-up, either because of (a) loss to follow-up, (b) mortality due to cause of interest, or (c) other causes of death. The risk ratio, or relative risk (RR) = ( died cause of interest in exposed/E person years)/( died cause of interest controls/E person years)...

In the normal incidence case presented here, the internal and scattered waves are of the same mode and polarization as the incident wave (mixing of the polarizations occurs when the incident wave is at an oblique angle). This yields two limiting cases for the internal electric field [10] ... 

Despite the high prevalence of the use of minor analgesics (aspirin and paracetamol) there is little information available on the association between the use of these analgesics and the risk of hypertension. A prospective cohort study in 80 020 women aged 31-50 years has provided some useful information (5). The women had participated in the Nurses Health Study II and had no previous history of hypertension. The frequency of use of paracetamol, aspirin, and NSAIDs was collected by mailed questionnaires and cases of physician-diagnosed hypertension were identified by self-report. During 164 000 person-years of follow-up, 1650 incident cases of hypertension were identified. Overall, 73% of the cohort had used paracetamol at least 1-4 days/month, 51% had used aspirin, and 77% had used an NS AID. Compared with non-users of paracetamol the age-adjusted relative risk... 

Since the publication of these two early studies, a number of studies have adopted a more prospective cohort approach to the examination of statin use in patients who develop dementia and AD over the course of a set period (usually between 5-10yrs). While many of the subsequent studies described seemingly protective effects in cross-sectional case-control analysis [36,45-51], the majority of prospective cohort analysis failed to identify a reduced risk of dementia in incident cases of dementia or AD [36, 46,47,51[. One notable exception comes from a study that examined a population identified by common AD risk facfors and co-morbidities (e.g., first degree relatives) [52]. In a high AD risk population, statin use was associated with a lowered risk of AD [52]. A summary of the epidemiological findings for stafin use in AD are shown in Table 1. 

In a proportionate mortality or proportionate incidence study, one compares the proportion of deaths or incident cases due to a condition of interest with that expected based on deaths or incident cases in an external, usually the general, population. When the proportions of causes of death are compared, the ratio is known as the proportionate mortality ratio (PMR). The comparison of proportions of incident cases is known as the proportionate incidence ratio (PIR). Proportional measures can be misleading since a decrement in the proportion of deaths or incident cases due to a particular cause will de facto lead to an increase in the proportion due to another cause. The commonly held view with regard to PMRs is that they are good approximations to SMRs from cohort studies when the cohort s all-canses combined SMR is equal to 1.0 (Checkoway et al. 1989). The odds ratio has also been used as a measure of association in PMR or PIR studies and may be a more appropriate measure of association for evalnating proportional measures (WHO 1999). 

Cohort study (incidence rate) and nested case-control M (10,486) Gold miners (incident cases) High incidence (8.2 per 100 000 person years), but no difference in exposure measures between cases and controls Cowie (1987)... 

Case-control Incident cases Plus prevalent cases (pooled analysis) M + F (235, 752) (515, 1257) Men OR 1.5-3.0 for various solvent-related occupations Women OR > 3.0 for printmakers and engravers Olsson et al. (2004)... 

The Scottish Motor Neuron Research Group (1992) The Scottish motor neuron disease register a prospective study of adult onset motor neuron disease in Scotland. Methodology, demography and clinical features of incident cases in 1989. J. Neurol. Neurosurg. Psychiatry 55 536-541. 

Figure 78.6 Age standardized incidence (cases per 100,000 inhabitants per year) of all thyroid cancer during the period 1971-2005 In western Sweden (Inhabitants 1.6 millions) compared to Sweden In total. There Is neither any observable trend for the different time periods nor can a difference be observed between western Sweden and Sweden in total.

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