Background

Skin cancer is an increasing health risk factor all over the world. Occurring from ultraviolet (UV) radiation combined with impairing ozone levels, uncritical sun exposure and use of tanning beds and increasing number of people are affected by different types of skin cancer. The incidences of non-melanoma skin cancer account for 2–3 million and for malignant melanoma 132 000 annually worldwide.1 The burdens of illness in melanoma and non-melanoma skin cancer are multifaceted and affect sick persons, family members, as well as the society and furthermore governmental institutions as responsible instance for all individuals in a country.

By causing slight symptoms in the early stages, persons suffering from skin cancer often run into high stages of illness. Delayed medical attention in higher stages demand a more invasive and cost-intensive therapy. Also, patients undergo losses in their quality of life from symptoms and invasive therapy. Accompanied losses of income from absenteeism in patients as well as in their caregiving family members appear. Despite continually increasing incidences in skin cancer entities like malignant melanoma (MM), basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) most people are still misunderstanding the hazard from UV radiation from sun or tanning beds. The use of sunbeds has been identified as the most significant risk increasing factor of melanoma and non-melanoma skin cancer.2 Over 65% of whites aged 18–29 years reported at least one sunburn in the past 12 months in the USA.3

Prevention strategies in each stage, primary, secondary and tertiary are in high demand. But interventions like skin cancer screening are still missing the evidence for effectiveness and therefore are criticised. A prerequisite should be, however, the critical application of the defined parameters as measures for effectiveness.

In the current literature, there is no distinct evidence for the effectiveness of skin cancer screening for example. Endpoints like mortality and morbidity increases are employed to prove the effectiveness of screening. But endpoints like these need an adjusted view on the stage of prevention, a corresponding time horizon, the perspective of account and so on.

Still studies rated in high quality by evidence-based medicine like randomised clinical trials (RCT), observational studies, ecological studies were taken into consideration. The recent issue is the report from the US Preventive Services Task Force by Wernli et al.4

Certainly, prevention interventions have to be characterised as complex interventions. The Medical Research Council defines some key features for complex interventions as:

• Number of interacting components;

• Number and difficulty of behaviours required by those delivering or receiving the intervention;

• Number of groups or organisational levels targeted by the intervention;

• Number and variability of outcomes;

• Non-pharmacological;

• Behavioural;

• Lack of linear, well-evidenced causal pathways linking between interventions and the health outcomes as well as

• Feedback loops, synergies and phase changes.5

All interventions of prevention primary, secondary and tertiary can be classified as complex interventions by fulfilling all the mentioned key features. Therefore, they should be handled with approaches that include more study designs besides RCTs and similar controlled designs. To understand and evaluate complex interventions there is a need for quasiexperimental study designs, using control/comparison groups/areas and also uncontrolled studies for example, time series analysis, before-and-after studies and so on.

Further multiple players in the complex interventions of prevention are affecting the process and influencing the outcomes. The WHO defined the different participants and structures that are involved in the process of implementation, execution, maintenance and continuous modification of preventive and curative interventions within the technical brief ‘integrated health services’.6 This approach is adopted to clarify the delivery of services or interventions and the acceptance or claim of interventions. The defined different levels such as the micro level for the ‘user’ or ‘patient’, the meso level for the ‘provider’ or ‘professionals’ and the macro level for ‘policy-makers’ by deciding, financing and regulating health services are employed.6 These different levels show the circumstances that can be understood as the ‘context’ for an intervention and will be henceforth be referred to as ‘organisational levels’. Interventions are highly context sensitive and on the other side the context is complex and often poorly anticipated and accommodating to interventions. The ‘double complexity’ of intervention and context and their interaction is a central and important issue, which is essential and necessarily to be evaluated or at least mentioned.7 To exceed a broad outline of the organisational levels, each is examined in several dimensions. Therefore, Donabedian’s framework for quality improvement8 is adduced. Structure, process and outcome can be evaluated on that base. Structure is defined by permanent capabilities of provider and requirement of user. The process covers all activities of each participant in the intervention, and the outcome concerns all results from produced and demanded performances.

Against this background, an analytical framework has been conceptualised which is examining the diversity of the structures in complex interventions of prevention and also interactions in the context. Research questions are conceived for different levels. Divers expected and factual effects as well as outcomes are implemented in this framework.

Relevance of review

This review seeks to outline effects of medical, social, communicative and economical aspects relevant for complex interventions in prevention in different skin cancer stages with the understanding of health services research.

Based on two scientifically established theories, the natural history of disease and the steps of prevention, this framework (figure 1) provides a working basis to point out key questions for the review. The effects and outcomes in the different levels with concomitant interactions can be displayed graphically.

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Figure 1

Analytical framework.

In this framework three main issues are in focus:

1. Prevention stage: each stage of prevention implicates specific interventions. In secondary prevention for example, screening can be provided. In primary prevention entirely different approaches have to be utilised.

2. Time horizon: time progression figures into several aspects, which are reciprocally combined. So the time horizon has to be considered in natural history of disease and also in proceeding prevention stages from primary to tertiary. The choice of time frame or point in time has high impact on the effects of prevention such as overdiagnosis in screenings for example.

3. Participants and structure in the process of prevention: patients, professionals and in the end the whole society have to be included in the evaluation process of complex interventions. These players have influence with their behaviours, decisions, skills, and so on and consequently influence the given context for complex interventions where they have to operate within. These participants and their specific perspective implicate divergent aspects of effects (benefits and costs) which all have to be considered individually. The participants and their perspectives are displayed in the different ‘organisational levels’ (macro, meso and micro) based on the WHO working definition on integrated health services.6 Within each level, the structure, process and outcome that result from interactions are considered.