Work-related well-being of Finnish anesthesiologists

Anesthesiologists, according to some studies, are highly stressed, die at a significantly earlier age than their colleagues and the general population,and are among the leaders in physicians' suicide records. Data are,however, sparse and contradictory. The aim of this study was to discover details of the work-related well-being of Finnish anesthesiologists. In 2004, a cross-sectional postal survey including all 550 working Finnish anesthesiologists produced a total of 328 responses (60%); 53% were men. The anesthesiologists had the greatest on-call workload among Finnish physicians. Their average in-hospital on-call period lasted 24 hours (range 14 to 38). Over two-thirds felt stressed. The most important causes of stress were work and combining work with family. Their main worries at work were: excessive workload and time constraints, especially being on call, organizational problems, and fear of harming patients. On-call workload correlated with burnout. Being frequently on call was correlated with severe stress symptoms--symptoms associated with sick leaves. Women were more affected by stress than men. High job control and organizational justice seemed to mitigate hospital-on-call stress symptoms. The respondents enjoyed fairly high job and life satisfaction. Job control and organizational justice were the most important correlates of these wellness indicators. Work-related factors were more important in males, whereas family life played a larger role in the well-being of female anesthesiologists. Women had less job control, fewer permanent job contracts, and a higher domestic workload. Of the respondents, 31% were willing to consider changing to another physician's specialty and 43% to a profession other than medicine. The most important correlates for these job turnover attitudes were conflicts at the workplace, low job control, organizational injustice, stress, and job dissatisfaction. One in four had at some time considered suicide. Respondents with poor health, low social support, and family problems were at the highest risk for suicidality. The highest risks at work were conflicts with co-workers and superiors, on-call-related stress symptoms, and low organizational justice. If a respondent had several risk factors, the risk for suicidality doubled with each additional factor. On-call work-burden, job control, fairness of decision-making procedures,and workplace relationships should be the focus in attempts to increase the work-related well-being of anesthesiologists.

Women, environmental changes and forestry-related development : Gender-affected roles of rural people in land degradation and environmental rehabilitation in a dry region of Sudan

The purpose of the present study was to increase understanding of the interaction of rural people and, specifically, women with the environment in a dry area in Sudan. The study that included both nomadic pastoralists and farmers aimed at answering two main research questions, namely: What kinds of roles have the local people, and the women in particular, had in land degradation in the study area and what kinds of issues would a gender-sensitive, forestry-related environmental rehabilitation intervention need to consider there? The study adopted the definition of land degradation as proposed by the United Nations Convention to Combat Desertification (UNCCD), which describes land degradation as reduction or loss the biological or economic productivity and complexity of land in arid, semi-arid and dry sub-humid areas. The Convention perceives desertification as land degradation. The dry study area in Sudan, South of the Sahara, has been the subject of land degradation or desertification discussions since the 1970s, and other studies have been also conducted to assess the degradation in the area. Nevertheless, the exact occurrence, scale and local significance of land degradation in the area is still unclear. This study explored how the rural population whose livelihood depended on the area, perceived environmental changes occurring there and compared their conceptions with other sources of information of the area such as research reports. The main fieldwork methods included interviews with open-ended questions and observation of people and the environment. The theoretical framework conceptualised the rural population as land users whose choices of environmental activities are affected by multiple factors in the social and biophysical contexts in which they live. It was emphasised that these factors have their own specific characteristics in different contexts, simultaneously recognising that there are also factors that generally affect environmental practices in various areas such as the land users' environmental literacy (conceptions of the environment), gender and livelihood needs. The people studied described that environmental changes, such as reduced vegetation cover and cropland production, had complicated the maintenance of their livelihoods in the study area. Some degraded sites were also identified through observations during the fieldwork. Whether a large-scale reduction of cropland productivity had occurred in the farmers' croplands remained, however, unclear. The study found that the environmental impact of the rural women's activities varied and was normally limited. The women's most significant environmental impact resulted from their cutting of trees, which was likely to contribute, at least in some places, to land degradation, affecting the environment together with climate and livestock. However, when a wider perspective is taken, it becomes questionable whether the women have really played roles in land degradation, since gender, poverty and the need to maintain livelihood had caused them to conduct environmentally harmful activities. The women have had, however, no power to change the causes of their activities. The findings further suggested that an inadequate availability of food was the most critical problem in the study area. Therefore, an environmental programme in the area was suggested to include technical measures to increase the productivity of croplands, opportunities for income generation and readiness to co-operate with other programmes to improve the local people's abilities to maintain their livelihoods. In order to protect the environment and alleviate the women's work burden, the introduction of fuel-saving stoves was also suggested. Furthermore, it was suggested that increased planting of trees on homesteads would be supported by an easy availability of tree seedlings. Planting trees on common property land was, however, perceived as extremely demanding in the study area, due to scarcity of such land. In addition, it became apparent that the local land users, and women in particular, needed to allocate their labour to maintain the immediate livelihood of their families and were not motivated to allocate their labour solely for environmental rehabilitation. Nonetheless, from the point of view of the existing social structures, women's active participation in a community-based environmental programme would be rather natural, particularly among the farmer women who had already formed a women's group and participated in communal decision making. Forming of a women group or groups was suggested to further support both the farmer women's and pastoral women's active participation within an environmental programme and their general empowerment. An Environmental programme would need to acknowledge that improving rural people's well-being and maintaining their livelihood in the study area requires development and co-operation with various sectors in Sudan.

Mammographic mass-screening and future breast cancer burden in Finland

A population-based early detection program for breast cancer has been in progress in Finland since 1987. According to regulations during the study period 1987-2001, free of charge mammography screening was offered every second year to women aged 50-59 years. Recently, the screening service was decided to be extended to age group 50-69. However, the scope of the program is still frequently discussed in public and information about potential impacts of mass-screening practice changes on future breast cancer burden is required. The aim of this doctoral thesis is to present methodologies for taking into account the mass-screening invitation information in breast cancer burden predictions, and to present alternative breast cancer incidence and mortality predictions up to 2012 based on scenarios of the future screening policy. The focus of this work is not on assessing the absolute efficacy but the effectiveness of mass-screening, and, by utilizing the data on invitations, on showing the estimated impacts of changes in an existing screening program on the short-term predictions. The breast cancer mortality predictions are calculated using a model that combines incidence, cause-specific and other cause survival on individual level. The screening invitation data are incorporated into modeling of breast cancer incidence and survival by dividing the program into separate components (first and subsequent rounds and years within them, breaks, and post screening period) and defining a variable that gives the component of the screening program. The incidence is modeled using a Poisson regression approach and the breast cancer survival by applying a parametric mixture cure model, where the patient population is allowed to be a combination of cured and uncured patients. The patients risk to die from other causes than breast cancer is allowed to differ from that of a corresponding general population group and to depend on age and follow-up time. As a result, the effects of separate components of the screening program on incidence, proportion of cured and the survival of the uncured are quantified. According to the predictions, the impacts of policy changes, like extending the program from age group 50-59 to 50-69, are clearly visible on incidence while the effects on mortality in age group 40-74 are minor. Extending the screening service would increase the incidence of localized breast cancers but decrease the rates of non-localized breast cancer. There were no major differences between mortality predictions yielded by alternative future scenarios of the screening policy: Any policy change would have at the most a 3.0% reduction on overall breast cancer mortality compared to continuing the current practice in the near future.

Work Stress and Early Atherosclerosis: Do Genetic Background and Pre-Employment Risk Factors Explain Conflicting Findings?

According to the models conceptualizing work stress, increased risk of health problems arise when high job demands co-occur with low job control (the demand-control model) or the efforts invested by the employee are disproportionately high compared to the rewards received (effort-reward imbalance model). This study examined the association between work stress and early atherosclerosis with particular attention to the role of pre-employment risk factors and genetic background in this association. The subjects were young healthy adults aged 24-39 who were participating in the 21-year follow-up of the ongoing prospective "Cardiovascular Risk in Young Finns" study in 2001-2002. Work stress was evaluated with questionnaires on demand-control model and on effort-reward model. Atherosclerosis was assessed with ultrasound of carotid artery intima-media thickness (IMT). In addition, risk for enhanced atherosclerotic process was assessed by measuring with heart rate variability and heart rate. Pre-employment risk factors, measured at age 12 to 18, included such as body mass index, blood lipids, family history of coronary heart disease, and parental socioeconomic position. Variants of the neuregulin-1 were determined using genomic DNA. The results showed that higher work stress was associated with higher IMT in men. This association was not attenuated by traditional risk factors of atherosclerosis and coronary heart disease or by pre-employment risk factors measured in adolescence. Neuregulin-1 gene moderated the association between work stress and IMT in men. A significant association between work stress and IMT was found only for the T/T genotype of the neuregulin-1 gene but not for other genotypes. Among women an association was found between higher work stress and lower heart rate variability, suggesting higher risk for developing atherosclerosis. These associations could not be explained by demographic characteristics or coronary risk factors. The present findings provide evidence for an association between work stress and atherosclerosis in relatively young population. This association seems to be modified by genetic influences but it does not appear to be confounded by pre-employment adolescent risk factors.

Childhood and adolescent antecedents of work stress and early atherosclerosis

Work stress is after musculoskeletal disorders the second most common work-related health problem in the European Union, affecting 28% of EU employees. Furthermore, a 50% excessive cardiovascular disease risk among employees with work stress is reported. High job demands combined with low job control according to the Job Demands-Job Control model, or high effort combined with low rewards according to Effort-Reward Imbalance model, are likely to produce work stress in the majority of employees. Atherosclerotic wall thickening is a validated marker of an increased risk of cardiovascular disease. This study examined the role of childhood and adolescent factors as antecedents of work stress and early atherosclerosis, and in the relationship between them. The Cardiovascular Risk in Young Finns Study, (the CRYF project) started in 1980 when the participants were at the age of three to 18 years. Follow-ups have been conducted every three years until 1992, after that in 1997 and 2001, and the latest is ongoing in 2008. The participants parents reported their socioeconomic position in 1980 and 1983, and their life satisfaction in 1983. Biological risk factors were measured in 1980 and 2001. Type A behaviour was reported in 1986, 1989 and 2001. In the 2001 follow-up when the participants were aged 24 to 39, work stress was assessed from responses to questionnaires on job demands-job control and effort-reward imbalance, and education. Ultrasound measurement of the carotid intima-media thickness (CIMT) was used to assess atherosclerosis. There were 755, 746, 1014 and 494 participants in studies I-IV, respectively. The results showed that low parental socioeconomic position and parental life dissatisfaction during childhood and adolescence predicted higher levels of job strain 18 years later, and that education mediated the relationship between parental socioeconomic position and job strain. Childhood and adolescent family factors were not related to the effort-reward imbalance. Parental life satisfaction was associated with high rewards at work among the men, and high parental socioeconomic position was associated with high reward among the women. Among the men, the eagerness-energy component of Type A behaviour across different developmental periods predicted increased CIMT. Among the women, hard-driving component of Type A behaviour predicted decreased CIMT. Low leadership characteristic in adolescence and early adulthood was associated with both high job strain and increased CIMT, and attenuated the relationship between job strain and CIMT to non-significance in men. The current findings add to the literature on the relationship between job strain and health literature in adopting a developmental perspective. The results imply that work stress does not completely originate from work. There are childhood and adolescent environmental and dispositional effects on work stress and CIMT several years later, and these partly seem to operate through educational attainment.

Self-reported bruxism : Associated factors among media personnel with or without irregular shift work

Tutkimuksen kohderyhmänä oli mediatyöntekijöitä, joiden toimenkuva on viime vuosina muuttunut yhä kuormittavammaksi epäsäännöllisen vuorotyön sekä jatkuvien teknisten, organisatoristen ja taloudellisten tekijöiden ristipaineessa. Väitöskirjatutkimus on osa laajempaa tutkimushanketta, joka suunniteltiin selvittämään epäsäännöllisen vuorotyön mahdollisia haittoja. Tutkimusta tukivat taloudellisesti Työsuojelurahasto ja Suomen Hammaslääkäriseura Apollonia sekä resurssipanostuksin Hammaslääketieteen laitos (HY), Työterveyslaitos ja Yleisradio Oy. Bruksismi on tahdosta riippumatonta hampaiden narskuttelua tai yhteenpuristamista. Hampaiden narskuttelu on rytmistä jaksoittain toistuvaa puremalihasten toimintaa, joka esiintyy nukkuessa -tavallisimmin kevyen unen ja havahtumisjaksojen yhteydessä. Valveilla ollessa bruksismi on terveillä ihmisillä lähinnä hampaiden yhteenpuristamista. Yleisen käsityksen mukaan toistuvaa unibruksismia esiintyy noin 10 %:lla ja valveilla tapahtuvaa hampaiden yhteenpuristamista noin 20 %:lla. Aiemmin bruksismi kuului kansainvälisen unihäiriöluokituksen (ICSD 1997) mukaan unen erityishäiriöihin, mutta tuorein luokitus (ICSD 2005) listaa sen unen liikehäiriöihin. Väitöstutkimuksen yleisenä tavoitteena oli kartoittaa koetun bruksismin ja uni- valvehäiriöiden yhteyttä. Tutkimus oli poikittainen vertailututkimus epäsäännöllistä vuorotyötä ja säännöllisiä päivävuoroja tekevien välillä. Mielenkiinto kohdistui myös bruksismin ja kasvojen alueen kivun mahdolliseen yhteyteen. Lisäksi tutkimuksessa selvitettiin joidenkin tunnetusti unen laatua huonontavien psykososiaalisten, neurologisten ja fysiologisten tekijöiden yhteyttä koettuun bruksismiin. Tutkimuksen kohderyhmän muodosti 750 Yleisradion epäsäännöllistä vuorotyötä tekevää työntekijää. Vertailuryhmänä käytettiin samansuuruista satunnaistetusti valittua kaltaistettua Yleisradion työntekijäjoukkoa, joka tekee samankaltaista työtä, mutta säännöllisenä päivätyönä. Kohderyhmälle lähetettiin kyselylomakkeet, jotka kartoittivat koetun bruksismin lisäksi mm. tutkittavien taustatiedot, yleisen terveydentilan, yleisiä koettuja stressioireita ja tuntemuksia, kipuoireita, sekä unen laatua. Lisäksi esitettiin jaksamista ja työympäristöä koskevia kysymyksiä. Kyselyyn vastasi kaikkiaan 874 henkilöä. Kokonaisvastausprosentti oli 58,3 % (53,7 % miehiä). Epäsäännöllistä vuorotyötä tekevien vastausprosentti oli 82,3 % ja säännöllistä päivätyötä tekevien ryhmässä 34,3 %. Työtehtävät sisälsivät ohjelmien toimitus- ja tuottamistyötä, teknistä tuotanto- ja tukityötä, sekä esimies- ja hallintotyötä. Miesten keski-ikä vuorotyöryhmässä oli 45,0 (± 10,6) vuotta ja naisten keski-ikä 42,6 (± 10,7) vuotta, vastaavat luvut päivätyötä tekeville olivat 47,4 (± 9,7) ja 45,5 (± 10,1) vuotta. Vuorotyötä tekevistä oli miehiä 56,6 %, päivätyöryhmässä miehien osuus oli 46,7 %. Usein koettua bruksismia havaittiin koko tutkimusjoukossa 10,6 %:lla. Bruksismin esiintyvyydessä ei ollut merkitsevää eroa epäsäännöllistä vuorotyötä ja päivätyötä tekevien välillä. Kun bruksismia ja stressiä arvioitiin suhteessa tyytyväisyyteen nykyiseen työaikamuotoon, molemmat olivat merkitsevästi vallitsevimpia niillä, jotka halusivat vaihtaa nykyistä työaikamuotoaan. Epäsäännöllistä vuorotyötä tekevät lisäksi ilmoittivat kokevansa enemmän stressiä kuin päivätyötä tekevät sekä olivat tyytymättömämpiä työaikamuotoonsa. Tutkittavista henkilöistä katkonaista unta esiintyi 43,6 %:lla sekä 36,2 % koki unensa virkistämättömäksi. Kasvokipua esiintyi 19,6 %:lla. Usein toistuva bruksaus sekä tyytymättömyys työaikamuotoon olivat erittäin merkitsevästi yhteydessä unihäiriöiden sekä riittämättömän unen oireiden kanssa. Bruksismi ja katkonainen uni osoittautuivat myös kasvokivun taustatekijöiksi. Tutkimus osoitti, että koetulla bruksismilla oli merkitsevä yhteys unihäiriöihin, kasvokipuun, koettuun stressiin ja ahdistuneisuuteen, nuorempaan ikään, runsaampiin hammaslääkäri- ja lääkärikäynteihin sekä siihen että oli tyytymätön työaikamuotoonsa (itse työaikamuoto ei ollut merkitsevä tekijä). Tutkimuksen yhtenä johtopäätöksenä todettiin, että koettu bruksismi voi terveillä työikäisillä henkilöillä olla osa stressaavaa tilannetta ja siihen liittyvää käyttäytymistä. Tämän tiedostaminen terveydenhuollossa voisi olla hyödyllistä.

Oral Cancer in Tehran, Iran: An approach for understanding disease burden

Suusyöpä Teheranissa, Iranissa 1993-2003 Tämän väitöskirjan tavoitteena oli kuvata suusyövän yleisyyttä ja siihen vaikuttavia tekijöitä Teheranissa, Iranissa tutkimalla suusyöpäpotilaita, suusyöpäkasvainten ominaisuuksia, potilaille tehtyjä diagnooseja ja niiden viivästymistä sekä heidän selviytymistä sairaudestaan. Suusyöpäkasvainten tietoja kerättiin 1042 suusyöpäpotilaalta. Nämä tiedot kerättiin 30 suurimman Teheranilaissairaalan potilaskortistoista vuosien 1993-2003 ajalta. Eloonjäämisanalyysiä varten tiedot kerättiin vuosien 1996-2003 arkistoista 470 suusyöpä- ja 82 huulisyöpäpotilaan osalta ja heitä seurattiin vuoden 2005 loppuun. Potilaan kokemien ensioireiden ja lopullisen syöpädiagnoosin välistä viivettä varten kerättiin tiedot Teheranilaisista sairaaloista 100 peräkkäisen suusyöpäpotilaan tiedoista vuosien 2004-2006 välillä. Ns diagnostinen viive jaettiin kahteen osaan: 1) ensioireiden ja ensimmäisen sitä seuranneen lääkärikäynnin väli ja 2) ensimmäisen lääkärikäynnin ja lopullisen diagnoosin välinen ero. Useimmat suusyövät olivat pitkälle edenneitä diagnoosin tekemisen hetkellä, kasvain oli siis yli 4 senttimetriä halkaisijaltaan ja/tai kaulan alueen imusolmukkeissa oli jo etäpesäkkeitä. Eloonjäämistodennäköisyys viiden vuoden aikavälillä oli suusyöpäpotilaille 30% ja huulisyöpäpotilaille 62%, mitkä olivat merkittävästi alempia kuin yleisesti länsimaissa vastaavat luvut. Tämä tutkimus osoitti, että keskimääräinen diagnostinen viive oli korkea (7,2 kk, SD 7,5), erityisesti kun niitä verrataan kehittyneimpien terveydenhuoltojärjestelmien vastaaviin tietoihin. Yleensä potilaasta aiheutuva viive oli huomattavan suuri ensioireiden ja lopullisen diagnoosin välisestä ajasta. Tässä tutkimuksessa tehtyjen havaintojen pohjalta on perusteltua esittää kehitettäväksi ennaltaehkäisevä tiedotusohjelma, jossa kansalaiset voisivat saada enemmän tietoa suusyövästä, sen ensioireista jotta he hakeutuisivat aikaisemmin hoitoon. Lisäksi terveydenhoitohenkilöstöä, erityisesti hammaslääkärejä ja suuhygienistejä tulisi kouluttaa varhaisen diagnoosin tekemiseksi, jotta Iranissa tehtävien suusyöpähoitojen lopputulokset paranisivat.

Cancer survivors at work : Work-related problems and factors associated with their employment, work ability and social support from the work community

Due to the improved prognosis of many forms of cancer, an increasing number of cancer survivors are willing to return to work after their treatment. It is generally believed, however, that people with cancer are either unemployed, stay at home, or retire more often than people without cancer. This study investigated the problems that cancer survivors experience on the labour market, as well as the disease-related, sociodemographic and psychosocial factors at work that are associated with the employment and work ability of cancer survivors. The impact of cancer on employment was studied combining the data of Finnish Cancer Registry and census data of the years 1985, 1990, 1995 or 1997 of Statistics Finland. There were two data sets containing 46 312 and 12 542 people with cancer. The results showed that cancer survivors were slightly less often employed than their referents. Two to three years after the diagnosis the employment rate of the cancer survivors was 9% lower than that of their referents (64% vs. 73%), whereas the employment rate was the same before the diagnosis (78%). The employment rate varied greatly according to the cancer type and education. The probability of being employed was greater in the lower than in the higher educational groups. People with cancer were less often employed than people without cancer mainly because of their higher retirement rate (34% vs. 27%). As well as employment, retirement varied by cancer type. The risk of retirement was twofold for people having cancer of the nervous system or people with leukaemia compared to their referents, whereas people with skin cancer, for example, did not have an increased risk of retirement. The aim of the questionnaire study was to investigate whether the work ability of cancer survivors differs from that of people without cancer and whether cancer had impaired their work ability. There were 591 cancer survivors and 757 referents in the data. Even though current work ability of cancer survivors did not differ between the survivors and their referents, 26% of cancer survivors reported that their physical work ability, and 19% that their mental work ability had deteriorated due to cancer. The survivors who had other diseases or had had chemotherapy, most often reported impaired work ability, whereas survivors with a strong commitment to their work organization, or a good social climate at work, reported impairment less frequently. The aim of the other questionnaire study containing 640 people with the history of cancer was to examine extent of social support that cancer survivors needed, and had received from their work community. The cancer survivors had received most support from their co-workers, and they hoped for more support especially from the occupational health care personnel (39% of women and 29% of men). More support was especially needed by men who had lymphoma, had received chemotherapy or had a low education level. The results of this study show that the majority of the survivors are able to return to work. There is, however, a group of cancer survivors who leave work life early, have impaired work ability due to their illness, and suffer from lack of support from their work place and the occupational health services. Treatment-related, as well as sociodemographic factors play an important role in survivors' work-related problems, and presumably their possibilities to continue working.

Musculoskeletal disorders and psychosocial factors at work : Effects of a participatory ergonomics intervention in a cluster randomized controlled trial

This study examined the efficacy of a participatory ergonomics intervention in preventing musculoskeletal disorders (MSDs) and changing unsatisfactory psychosocial working conditions among municipal kitchen workers. The occurrence of multiple-site musculoskeletal pain (MSP) and associations between MSP and psychosocial factors at work over time were studied secondarily. A cluster randomized controlled trial was conducted during 2002-2005 in 119 municipal kitchens with 504 workers. The kitchens were randomized to an intervention (n = 59) and control (n = 60) group. The intervention lasted 11 to 14 months. The workers identified strenuous work tasks and sought solutions for decreasing physical and mental workload. The main outcomes were the occurrence of and trouble caused by musculoskeletal pain in seven anatomical sites, local musculoskeletal fatigue after work, and musculoskeletal sick leaves. Psychosocial factors at work (job control, skill discretion, co-worker relationships, supervisor support, mental strenuousness of work, hurry, job satisfaction) and mental stress were studied as intermediate outcomes of the intervention. Questionnaire data were collected at three months intervals during the intervention and the one-year post-intervention follow-up. Response rates varied between 92 % and 99 %. In total, 402 ergonomic changes were implemented. In the control group, 80 changes were spontaneously implemented within normal activity. The intervention did not reduce perceived physical workload and no systematic differences in any health outcomes were found between the intervention and control groups during the intervention or during the one-year follow-up. The results suggest that the intervention as studied in the present trial was not more effective in reducing perceived physical workload or preventing MSDs compared with no such intervention. Little previous evidence of the effectiveness of ergonomics interventions in preventing MSDs exists. The effects on psychosocial factors at work were adverse, especially in the two of the participating cities where re-organization of foodservices timed simultaneously with the intervention. If organizational reforms at workplace are expected to occur, the execution of other workplace interventions at the same time should be avoided. The co-occurrence of musculoskeletal pain at several sites is observed to be more common than pain at single anatomical sites. However, the risk factors of MSP are largely unknown. This study showed that at baseline, 73 % of the women reported pain in at least two, 36 % in four or more, and 10 % in six to seven sites. The seven pain symptoms occurred in over 80 different combinations. When co-occurrence of pain was studied in three larger anatomical areas (neck/low back, upper limbs, lower limbs), concurrent pain in all three areas was the most common combination (36 %). The 3-month prevalence of MSP (≥ 3 of seven sites) varied between 50 % and 61 % during the two-year follow-up period. Psychosocial factors at work and mental stress were strong predictors for MSP over time and, vice versa, MSP predicted psychosocial factors at work and mental stress. The reciprocality of the relationships implies either two mutually dependent processes in time, or some shared common underlying factor(s).